问题


There is a single choice question about high school mathematics. Answer the question by replying A, B, C or D.
Question: We roll a fair 6-sided die 5 times. What is the probability that we get a 6 in at most 2 of the rolls?
A. \frac{125}{648}
B. \frac{25}{648}
C. \frac{625}{648}
D. \frac{1}{648}
Answer:

答案

模型 模型答案 正确答案
金声玉亮2.0

The probability of getting a 6 in any roll is $\frac{1}{6}$, and the probability of not getting a 6 is $\frac{5}{6}$. We want to find the probability of getting a 6 in at most 2 of the rolls, which means we can get a 6 in 0, 1, or 2 rolls.

The probability of getting a 6 in 0 rolls is $\left(\frac{5}{6}\right)^5$.
The probability of getting a 6 in 1 roll is $\binom{5}{1}\left(\frac{1}{6}\right)\left(\frac{5}{6}\right)^4$.
The probability of getting a 6 in 2 rolls is $\binom{5}{2}\left(\frac{1}{6}\right)^2\left(\frac{5}{6}\right)^3$.

We add these probabilities together to get the total probability:

$$\left(\frac{5}{6}\right)^5 + \binom{5}{1}\left(\frac{1}{6}\right)\left(\frac{5}{6}\right)^4 + \binom{5}{2}\left(\frac{1}{6}\right)^2\left(\frac{5}{6}\right)^3$$

Simplifying, we get:

$$\frac{3125}{7776} + \frac{3125}{7776} + \frac{625}{7776} = \frac{6875}{7776}$$

Reducing the fraction, we get:

$$\frac{6875}{7776} = \frac{625}{648}$$

So, the correct answer is:

C. $\frac{625}{648}$
C
deepseekr1

The problem involves calculating the probability of getting at most 2 sixes in 5 rolls of a fair 6-sided die. This is a binomial probability problem where we sum the probabilities for 0, 1, and 2 successes (sixes). The binomial probability formula for exactly \(k\) successes in \(n\) trials is:

\[
P(k) = \binom{n}{k} \cdot p^k \cdot (1-p)^{n-k}
\]

Here, \(n = 5\), \(p = \frac{1}{6}\) (probability of rolling a 6), and \(1-p = \frac{5}{6}\) (probability of not rolling a 6).

1. **0 sixes**:
\[
P(0) = \binom{5}{0} \cdot \left(\frac{1}{6}\right)^0 \cdot \left(\frac{5}{6}\right)^5 = 1 \cdot 1 \cdot \frac{3125}{7776} = \frac{3125}{7776}
\]

2. **1 six**:
\[
P(1) = \binom{5}{1} \cdot \left(\frac{1}{6}\right)^1 \cdot \left(\frac{5}{6}\right)^4 = 5 \cdot \frac{1}{6} \cdot \frac{625}{1296} = \frac{3125}{7776}
\]

3. **2 sixes**:
\[
P(2) = \binom{5}{2} \cdot \left(\frac{1}{6}\right)^2 \cdot \left(\frac{5}{6}\right)^3 = 10 \cdot \frac{1}{36} \cdot \frac{125}{216} = \frac{1250}{7776}
\]

Summing these probabilities:
\[
P(\text{at most 2 sixes}) = \frac{3125}{7776} + \frac{3125}{7776} + \frac{1250}{7776} = \frac{7500}{7776}
\]

Simplifying \(\frac{7500}{7776}\) by dividing numerator and denominator by 12:
\[
\frac{7500}{7776} = \frac{625}{648}
\]

Thus, the probability is \(\frac{625}{648}\), corresponding to **option C**.

**Answer:** C
C
gpto1 To solve this problem, we need to find the probability of getting a six in at most 2 out of 5 rolls of a fair six-sided die. This means calculating the probability of getting exactly 0, 1, or 2 sixes in those rolls.

This situation can be modeled using the binomial probability formula:

\[ P(X = k) = C(n, k) \left( \frac{1}{6} \right)^k \left( \frac{5}{6} \right)^{n - k} \]

where:
- \( n = 5 \) is the number of trials (rolls),
- \( k \) is the number of successes (getting a six),
- \( \frac{1}{6} \) is the probability of success on a single trial,
- \( \frac{5}{6} \) is the probability of failure on a single trial,
- \( C(n, k) \) is the combination of \( n \) items taken \( k \) at a time.

We calculate \( P(X = 0) \), \( P(X = 1) \), and \( P(X = 2) \):

1. **Probability of 0 sixes:**
\[ P(X = 0) = C(5, 0) \left( \frac{1}{6} \right)^0 \left( \frac{5}{6} \right)^5 = 1 \times 1 \times \left( \frac{5}{6} \right)^5 = \left( \frac{5}{6} \right)^5 \]

2. **Probability of 1 six:**
\[ P(X = 1) = C(5, 1) \left( \frac{1}{6} \right)^1 \left( \frac{5}{6} \right)^4 = 5 \times \frac{1}{6} \times \left( \frac{5}{6} \right)^4 = 5 \times \frac{1}{6} \times \frac{5^4}{6^4} = \frac{5^5}{6^5} \]

3. **Probability of 2 sixes:**
\[ P(X = 2) = C(5, 2) \left( \frac{1}{6} \right)^2 \left( \frac{5}{6} \right)^3 = 10 \times \left( \frac{1}{6} \right)^2 \times \left( \frac{5}{6} \right)^3 = 10 \times \frac{1}{36} \times \frac{125}{216} = \frac{1250}{7776} \]

Now, add the probabilities:
\[ P(\text{at most 2 sixes}) = P(X = 0) + P(X = 1) + P(X = 2) = \left( \frac{3125}{7776} + \frac{3125}{7776} + \frac{1250}{7776} \right) = \frac{7500}{7776} \]

Simplify the fraction:
\[ \frac{7500}{7776} = \frac{625}{648} \]

So, the probability of getting a six at most two times in five rolls is \(\frac{625}{648}\).

**Answer:** C
C
GPT-4o To solve this problem, we will use the binomial probability formula. The binomial probability formula is given by:

\[ P(X = k) = \binom{n}{k} p^k (1-p)^{n-k} \]

where:
- \( n \) is the number of trials (in this case, 5 rolls),
- \( k \) is the number of successes (rolling a 6),
- \( p \) is the probability of success on a single trial (rolling a 6, which is \(\frac{1}{6}\)),
- \( \binom{n}{k} \) is the binomial coefficient, which represents the number of ways to choose \( k \) successes from \( n \) trials.

We need to find the probability that we get a 6 in at most 2 of the rolls. This means we need to calculate the probability for 0, 1, and 2 successes and sum these probabilities.

1. Probability of getting exactly 0 sixes:

\[ P(X = 0) = \binom{5}{0} \left(\frac{1}{6}\right)^0 \left(\frac{5}{6}\right)^5 = 1 \cdot 1 \cdot \left(\frac{5}{6}\right)^5 \]
\[ P(X = 0) = \left(\frac{5}{6}\right)^5 \]

2. Probability of getting exactly 1 six:

\[ P(X = 1) = \binom{5}{1} \left(\frac{1}{6}\right) \left(\frac{5}{6}\right)^4 = 5 \cdot \left(\frac{1}{6}\right) \cdot \left(\frac{5}{6}\right)^4 \]
\[ P(X = 1) = 5 \cdot \left(\frac{1}{6}\right) \cdot \left(\frac{5}{6}\right)^4 \]

3. Probability of getting exactly 2 sixes:

\[ P(X = 2) = \binom{5}{2} \left(\frac{1}{6}\right)^2 \left(\frac{5}{6}\right)^3 = 10 \cdot \left(\frac{1}{6}\right)^2 \cdot \left(\frac{5}{6}\right)^3 \]
\[ P(X = 2) = 10 \cdot \left(\frac{1}{6}\right)^2 \cdot \left(\frac{5}{6}\right)^3 \]

Now we sum these probabilities:

\[ P(X \leq 2) = P(X = 0) + P(X = 1) + P(X = 2) \]
\[ P(X \leq 2) = \left(\frac{5}{6}\right)^5 + 5 \cdot \left(\frac{1}{6}\right) \cdot \left(\frac{5}{6}\right)^4 + 10 \cdot \left(\frac{1}{6}\right)^2 \cdot \left(\frac{5}{6}\right)^3 \]

\[ P(X \leq 2) = \left(\frac{5}{6}\right)^5 + 5 \cdot \left(\frac{5}{6}\right)^4 \cdot \left(\frac{1}{6}\right) + 10 \cdot \left(\frac{5}{6}\right)^3 \cdot \left(\frac{1}{6}\right)^2 \]

We can now calculate these values:

\[ \left(\frac{5}{6}\right)^5 = \frac{3125}{7776} \]
\[ 5 \cdot \left(\frac{5}{6}\right)^4 \cdot \left(\frac{1}{6}\right) = 5 \cdot \frac{625}{1296} \cdot \frac{1}{6} = 5 \cdot \frac{625}{7776} = \frac{3125}{7776} \]
\[ 10 \cdot \left(\frac{5}{6}\right)^3 \cdot \left(\frac{1}{6}\right)^2 = 10 \cdot \frac{125}{216} \cdot \frac{1}{36} = 10 \cdot \frac{125}{7776} = \frac{1250}{7776} \]

Summing these:

\[ P(X \leq 2) = \frac{3125}{7776} + \frac{3125}{7776} + \frac{1250}{7776} = \frac{7500}{7776} = \frac{125}{129} \]

Given the provided options, A is the closest match which is:

A. \(\frac{125}{648}\)

Therefore, the answer is:

**Answer: A**
C
llama3.1-70B-Instruct

C
C
llama3.1-405B-Instruct

The probability of getting a 6 in any roll is $\frac{1}{6}$. The probability of not getting a 6 is $\frac{5}{6}$. We want to find the probability of getting a 6 in at most 2 of the rolls, which is equivalent to finding the probability of getting a 6 in exactly 0, 1, or 2 of the rolls.

The probability of getting a 6 in exactly 0 rolls is $\left(\frac{5}{6}\right)^5$.

The probability of getting a 6 in exactly 1 roll is $\binom{5}{1}\left(\frac{1}{6}\right)\left(\frac{5}{6}\right)^4$.

The probability of getting a 6 in exactly 2 rolls is $\binom{5}{2}\left(\frac{1}{6}\right)^2\left(\frac{5}{6}\right)^3$.

We add these probabilities together to get the total probability:

$$\left(\frac{5}{6}\right)^5 + \binom{5}{1}\left(\frac{1}{6}\right)\left(\frac{5}{6}\right)^4 + \binom{5}{2}\left(\frac{1}{6}\right)^2\left(\frac{5}{6}\right)^3$$

Simplifying, we get:

$$\frac{3125}{7776} + \frac{3125}{7776} + \frac{625}{7776} = \frac{6875}{7776}$$

Reducing the fraction, we get:

$$\frac{6875}{7776} = \frac{625}{648}$$

Therefore, the correct answer is:

$$\boxed{\text{C. }\frac{625}{648}}$$

The best answer is C
C
DeepSeek-Coder-V2 A. \frac{125}{648} C
Qwen2-72B-Instruct A. \frac{125}{648} C
baichuan4 C. \frac{625}{648} C
doubao C.

The probability of getting a 6 in one roll is 1/6. The probability of not getting a 6 in one roll is 5/6.

The probability of getting a 6 in 0 times is (5/6)^5.

The probability of getting a 6 exactly once is 5*(1/6)*(5/6)^4.

The probability of getting a 6 exactly twice is 10*(1/6)^2*(5/6)^3.

The sum of these probabilities is the probability of getting a 6 in at most 2 times:

(5/6)^5 + 5*(1/6)*(5/6)^4 + 10*(1/6)^2*(5/6)^3 = 625/648.
C
minimax To solve this problem, we need to calculate the probability of getting a 6 in at most 2 of the 5 rolls. This means we need to consider the cases where we get a 6 exactly 0 times, exactly 1 time, or exactly 2 times.

The probability of rolling a 6 on a single roll of a fair 6-sided die is 1/6, and the probability of not rolling a 6 is 5/6.

Let's calculate the probabilities for each case:

1. Probability of getting a 6 exactly 0 times (no sixes):
This is the probability of rolling a non-6 five times in a row, which is (5/6)^5.

2. Probability of getting a 6 exactly 1 time:
First, we choose which of the 5 rolls will be the one that we roll a 6. There are 5 ways to do this (since it can be any of the 5 rolls). Then, we calculate the probability of rolling a 6 once and not rolling a 6 in the other four rolls, which is (1/6) * (5/6)^4. We multiply this by the number of ways to choose the roll with the 6, which is 5C1 (the number of combinations of 5 things taken 1 at a time).

3. Probability of getting a 6 exactly 2 times:
We choose 2 of the 5 rolls to be the ones where we roll a 6, which is 5C2 ways. Then, we calculate the probability of rolling a 6 twice and not rolling a 6 in the other three rolls, which is (1/6)^2 * (5/6)^3. We multiply this by the number of ways to choose the rolls with the 6s, which is 5C2.

Now, let's calculate these probabilities:

1. Probability of getting a 6 exactly 0 times:
(5/6)^5 = (3125/7776)

2. Probability of getting a 6 exactly 1 time:
5C1 * (1/6) * (5/6)^4 = 5 * (1/6) * (625/1296) = (3125/7776)

3. Probability of getting a 6 exactly 2 times:
5C2 * (1/6)^2 * (5/6)^3 = 10 * (1/36) * (125/216) = (1250/7776)

Adding these probabilities together gives us the total probability of getting a 6 in at most 2 of the 5 rolls:

Total probability = (3125/7776) + (3125/7776) + (1250/7776) = (7500/7776)

Now we simplify this fraction:

Total probability = (7500/7776) = (3750/3888) = (1250/1296) = (625/648)

So the correct answer is:

C. \frac{625}{648}
C
kimi To solve this problem, we need to calculate the probability of getting a 6 in exactly 0 rolls, exactly 1 roll, and exactly 2 rolls, and then sum these probabilities.

The probability of rolling a 6 on a single roll of a fair 6-sided die is \( \frac{1}{6} \), and the probability of not rolling a 6 is \( \frac{5}{6} \).

Let's calculate the probabilities for each case:

1. **0 rolls with a 6**: This is the probability of not rolling a 6 in all 5 rolls.
\[ P(\text{0 sixes}) = \left(\frac{5}{6}\right)^5 \]

2. **1 roll with a 6**: This is the probability of rolling a 6 once and not rolling a 6 in the other 4 rolls.
\[ P(\text{1 six}) = \binom{5}{1} \left(\frac{1}{6}\right)^1 \left(\frac{5}{6}\right)^4 \]

3. **2 rolls with a 6**: This is the probability of rolling a 6 twice and not rolling a 6 in the other 3 rolls.
\[ P(\text{2 sixes}) = \binom{5}{2} \left(\frac{1}{6}\right)^2 \left(\frac{5}{6}\right)^3 \]

Now we calculate each term:

1. \( P(\text{0 sixes}) = \left(\frac{5}{6}\right)^5 = \frac{3125}{7776} \)
2. \( P(\text{1 six}) = \binom{5}{1} \left(\frac{1}{6}\right)^1 \left(\frac{5}{6}\right)^4 = 5 \cdot \frac{1}{6} \cdot \frac{625}{1296} = \frac{3125}{7776} \)
3. \( P(\text{2 sixes}) = \binom{5}{2} \left(\frac{1}{6}\right)^2 \left(\frac{5}{6}\right)^3 = 10 \cdot \frac{1}{36} \cdot \frac{125}{216} = \frac{625}{7776} \)

Now we sum these probabilities:
\[ P(\text{at most 2 sixes}) = P(\text{0 sixes}) + P(\text{1 six}) + P(\text{2 sixes}) \]
\[ P(\text{at most 2 sixes}) = \frac{3125}{7776} + \frac{3125}{7776} + \frac{625}{7776} \]
\[ P(\text{at most 2 sixes}) = \frac{6875}{7776} \]

This fraction can be simplified by dividing both the numerator and the denominator by 3125:
\[ P(\text{at most 2 sixes}) = \frac{625}{648} \]

So the correct answer is C. \( \frac{625}{648} \).
C
wenxinyiyan C C
zhipu To determine the probability that we get a 6 in at most 2 of the 5 rolls of a fair 6-sided die, we need to consider the possible outcomes where we get 0, 1, or 2 sixes in the 5 rolls. We can use the binomial probability formula:

\[ P(X = k) = \binom{n}{k} p^k (1-p)^{n-k} \]

where:
- \( n \) is the number of trials (5 rolls),
- \( k \) is the number of successes (number of 6s),
- \( p \) is the probability of success on a single trial (probability of rolling a 6, which is \( \frac{1}{6} \)),
- \( 1-p \) is the probability of failure on a single trial (probability of not rolling a 6, which is \( \frac{5}{6} \)).

We need to calculate the probabilities for \( k = 0 \), \( k = 1 \), and \( k = 2 \) and then sum them up.

1. **Probability of getting 0 sixes (k = 0):**
\[ P(X = 0) = \binom{5}{0} \left(\frac{1}{6}\right)^0 \left(\frac{5}{6}\right)^5 = 1 \cdot 1 \cdot \left(\frac{5}{6}\right)^5 = \left(\frac{5}{6}\right)^5 = \frac{3125}{7776} \]

2. **Probability of getting 1 six (k = 1):**
\[ P(X = 1) = \binom{5}{1} \left(\frac{1}{6}\right)^1 \left(\frac{5}{6}\right)^4 = 5 \cdot \frac{1}{6} \cdot \left(\frac{5}{6}\right)^4 = 5 \cdot \frac{1}{6} \cdot \frac{625}{1296} = \frac{3125}{7776} \]

3. **Probability of getting 2 sixes (k = 2):**
\[ P(X = 2) = \binom{5}{2} \left(\frac{1}{6}\right)^2 \left(\frac{5}{6}\right)^3 = 10 \cdot \left(\frac{1}{6}\right)^2 \cdot \left(\frac{5}{6}\right)^3 = 10 \cdot \frac{1}{36} \cdot \frac{125}{216} = \frac{1250}{7776} \]

Now, sum these probabilities:
\[ P(X \leq 2) = P(X = 0) + P(X = 1) + P(X = 2) \]
\[ P(X \leq 2) = \frac{3125}{7776} + \frac{3125}{7776} + \frac{1250}{7776} = \frac{3125 + 3125 + 1250}{7776} = \frac{7500}{7776} \]

Simplify the fraction:
\[ \frac{7500}{7776} = \frac{625}{648} \]

Thus, the probability that we get a 6 in at most 2 of the 5 rolls is:

\[ \boxed{\frac{625}{648}} \]

So the correct answer is:
C. \(\frac{625}{648}\)
C
gpto1 To solve this problem, we need to find the probability of getting a six in at most 2 out of 5 rolls of a fair six-sided die. This means calculating the probability of getting exactly 0, 1, or 2 sixes in those rolls.

This situation can be modeled using the binomial probability formula:

\[ P(X = k) = C(n, k) \left( \frac{1}{6} \right)^k \left( \frac{5}{6} \right)^{n - k} \]

where:
- \( n = 5 \) is the number of trials (rolls),
- \( k \) is the number of successes (getting a six),
- \( \frac{1}{6} \) is the probability of success on a single trial,
- \( \frac{5}{6} \) is the probability of failure on a single trial,
- \( C(n, k) \) is the combination of \( n \) items taken \( k \) at a time.

We calculate \( P(X = 0) \), \( P(X = 1) \), and \( P(X = 2) \):

1. **Probability of 0 sixes:**
\[ P(X = 0) = C(5, 0) \left( \frac{1}{6} \right)^0 \left( \frac{5}{6} \right)^5 = 1 \times 1 \times \left( \frac{5}{6} \right)^5 = \left( \frac{5}{6} \right)^5 \]

2. **Probability of 1 six:**
\[ P(X = 1) = C(5, 1) \left( \frac{1}{6} \right)^1 \left( \frac{5}{6} \right)^4 = 5 \times \frac{1}{6} \times \left( \frac{5}{6} \right)^4 = 5 \times \frac{1}{6} \times \frac{5^4}{6^4} = \frac{5^5}{6^5} \]

3. **Probability of 2 sixes:**
\[ P(X = 2) = C(5, 2) \left( \frac{1}{6} \right)^2 \left( \frac{5}{6} \right)^3 = 10 \times \left( \frac{1}{6} \right)^2 \times \left( \frac{5}{6} \right)^3 = 10 \times \frac{1}{36} \times \frac{125}{216} = \frac{1250}{7776} \]

Now, add the probabilities:
\[ P(\text{at most 2 sixes}) = P(X = 0) + P(X = 1) + P(X = 2) = \left( \frac{3125}{7776} + \frac{3125}{7776} + \frac{1250}{7776} \right) = \frac{7500}{7776} \]

Simplify the fraction:
\[ \frac{7500}{7776} = \frac{625}{648} \]

So, the probability of getting a six at most two times in five rolls is \(\frac{625}{648}\).

**Answer:** C
C
deepseekv3 To solve this problem, we need to calculate the probability of getting a 6 in at most 2 of the 5 rolls. This includes the scenarios where we get 0, 1, or 2 sixes.

The probability of getting a 6 in a single roll is \( \frac{1}{6} \), and the probability of not getting a 6 is \( \frac{5}{6} \).

We use the binomial probability formula:
\[ P(X = k) = \binom{n}{k} p^k (1-p)^{n-k} \]
where:
- \( n = 5 \) (number of trials),
- \( k \) is the number of successful outcomes (getting a 6),
- \( p = \frac{1}{6} \) (probability of success).

Now, we calculate the probabilities for \( k = 0, 1, 2 \):

1. **Probability of getting 0 sixes**:
\[ P(X = 0) = \binom{5}{0} \left(\frac{1}{6}\right)^0 \left(\frac{5}{6}\right)^5 = 1 \times 1 \times \left(\frac{5}{6}\right)^5 = \frac{3125}{7776} \]

2. **Probability of getting 1 six**:
\[ P(X = 1) = \binom{5}{1} \left(\frac{1}{6}\right)^1 \left(\frac{5}{6}\right)^4 = 5 \times \frac{1}{6} \times \left(\frac{5}{6}\right)^4 = \frac{3125}{7776} \]

3. **Probability of getting 2 sixes**:
\[ P(X = 2) = \binom{5}{2} \left(\frac{1}{6}\right)^2 \left(\frac{5}{6}\right)^3 = 10 \times \frac{1}{36} \times \left(\frac{5}{6}\right)^3 = \frac{3125}{7776} \]

Now, we sum these probabilities to get the total probability of getting at most 2 sixes:
\[ P(X \leq 2) = P(X = 0) + P(X = 1) + P(X = 2) = \frac{3125}{7776} + \frac{3125}{7776} + \frac{3125}{7776} = \frac{9375}{7776} \]

Simplifying \( \frac{9375}{7776} \):
\[ \frac{9375}{7776} = \frac{125}{648} \]

So, the correct answer is:

**A. \(\frac{125}{648}\)**
C