问题


There is a single choice question about high school statistics. Answer the question by replying A, B, C or D.
Question: A dentist has noticed that about two children in every seven whom he sees professionally develop cavities before they turn 10 years old. Last week he examined the teeth of five unrelated children younger than 10. Let X be the number of children who develop cavities before turning 10. Which of the following gives the probability that at least one will develop a cavity before turning 10?
A. P(X = 2, 3, 4, 5, 6, 7)
B. P(X = 2 out of 7)
C. P(X = 1)
D. 1 – P(X = 0)
Answer:

答案

模型 模型答案 正确答案
金声玉亮2.0

D. 1 – P(X = 0)

Explanation:

The question asks for the probability that at least one child will develop a cavity before turning 10. To find this probability, we can use the complement rule, which states that the probability of an event occurring is equal to 1 minus the probability of the event not occurring.

In this case, the event is "at least one child develops a cavity before turning 10". The complement of this event is "no child develops a cavity before turning 10", which is equivalent to X = 0.

So, the probability that at least one child will develop a cavity before turning 10 is equal to 1 minus the probability that no child will develop a cavity before turning 10, which is P(X = 0).

Therefore, the correct answer is D. 1 – P(X = 0).
D
deepseekr1

The problem involves a binomial distribution where each child has a 2/7 probability of developing cavities. We need the probability that at least one out of five children develops a cavity. Using the complement rule, this is calculated as \(1 - P(X = 0)\), avoiding the need to sum probabilities for all cases where \(X \geq 1\).

- **Option A** incorrectly references impossible values (6, 7) for \(X\) since only 5 children are examined.
- **Option B** refers to an unrelated scenario (2 out of 7).
- **Option C** calculates only the probability of exactly one child, not "at least one."
- **Option D** correctly applies the complement rule.

**Answer: D**
D
gpto1 The problem is centered around calculating the probability that at least one out of five children will develop cavities before turning 10, given that the probability for any individual child is \( \frac{2}{7} \).

Let's rephrase the problem in probabilistic terms:
- The number of trials (children) \( n = 5 \)
- The probability of success (developing cavities) for each trial \( p = \frac{2}{7} \)
- We are to find \( P(X \geq 1) \) where \( X \) follows a binomial distribution \( X \sim \text{Binomial}(n=5, p=\frac{2}{7}) \)

**Option Analysis:**

**Option A:** \( P(X = 2, 3, 4, 5, 6, 7) \)
- This suggests summing the probabilities of getting 2 to 7 successes.
- However, since we only have 5 trials, \( X \) can range only from 0 to 5.
- Values for \( X = 6 \) or \( X = 7 \) are not possible.
- Therefore, this option is incorrect.

**Option B:** \( P(X = 2 \text{ out of } 7) \)
- This represents the probability of getting exactly 2 successes out of 7 trials.
- Our scenario involves 5 trials, not 7.
- This option does not relate directly to the problem.

**Option C:** \( P(X = 1) \)
- This is the probability of exactly one child developing cavities.
- The question asks for "at least one," which includes one or more children.
- This option only accounts for one specific case and ignores the others where more than one child might develop cavities.

**Option D:** \( 1 - P(X = 0) \)
- This is the complement of the probability that none of the children develop cavities.
- Since \( P(X \geq 1) = 1 - P(X = 0) \) for binomial distributions, this correctly represents the probability that at least one child develops cavities.
- This matches the requirement of the problem.

Hence, **Option D** is the correct representation.

**Answer:** D
D
GPT-4o D. 1 – P(X = 0) D
llama3.1-70B-Instruct

D
D
llama3.1-405B-Instruct

D. 1 – P(X = 0)

Explanation: The question asks for the probability that at least one child will develop a cavity before turning 10. This is equivalent to finding the probability that not all children will be cavity-free, which is 1 minus the probability that all children will be cavity-free (i.e., X = 0). Therefore, the correct answer is D. 1 – P(X = 0).
D
DeepSeek-Coder-V2 D D
Qwen2-72B-Instruct D. 1 – P(X = 0) D
baichuan4 D D
doubao D. 1 – P(X = 0). The probability that at least one will develop a cavity is 1 minus the probability that none of them develop a cavity (P(X = 0)). D
minimax D. 1 – P(X = 0)

This question is asking for the probability that at least one child will develop a cavity before turning 10. The easiest way to calculate this is to find the probability that none of the children develop a cavity and subtract that from 1. This gives the probability of the complementary event, which is that at least one child does develop a cavity.
D
kimi D. 1 – P(X = 0)

Explanation: The dentist has observed that approximately 2 out of every 7 children develop cavities before turning 10. If we let X be the number of children who develop cavities, we are looking for the probability that at least one child will develop a cavity.

The probability of a single child developing a cavity is 2/7, and the probability of a single child not developing a cavity is 5/7.

The probability that none of the five children develop cavities (P(X = 0)) would be (5/7)^5, because each child has a 5/7 chance of not developing a cavity, and we are assuming independence between the children.

To find the probability that at least one child will develop a cavity, we can use the complement rule, which states that the probability of at least one event happening is equal to 1 minus the probability of none of the events happening.

So, P(at least one cavity) = 1 - P(X = 0).
D
wenxinyiyan D D
zhipu D. 1 – P(X = 0)

The question asks for the probability that at least one of the five children will develop a cavity before turning 10. This can be calculated by finding the complement of the probability that none of the children develop a cavity, which is represented by P(X = 0). The complement of P(X = 0) is 1 – P(X = 0). Hence, the correct answer is D.
D
gpto1 The problem is centered around calculating the probability that at least one out of five children will develop cavities before turning 10, given that the probability for any individual child is \( \frac{2}{7} \).

Let's rephrase the problem in probabilistic terms:
- The number of trials (children) \( n = 5 \)
- The probability of success (developing cavities) for each trial \( p = \frac{2}{7} \)
- We are to find \( P(X \geq 1) \) where \( X \) follows a binomial distribution \( X \sim \text{Binomial}(n=5, p=\frac{2}{7}) \)

**Option Analysis:**

**Option A:** \( P(X = 2, 3, 4, 5, 6, 7) \)
- This suggests summing the probabilities of getting 2 to 7 successes.
- However, since we only have 5 trials, \( X \) can range only from 0 to 5.
- Values for \( X = 6 \) or \( X = 7 \) are not possible.
- Therefore, this option is incorrect.

**Option B:** \( P(X = 2 \text{ out of } 7) \)
- This represents the probability of getting exactly 2 successes out of 7 trials.
- Our scenario involves 5 trials, not 7.
- This option does not relate directly to the problem.

**Option C:** \( P(X = 1) \)
- This is the probability of exactly one child developing cavities.
- The question asks for "at least one," which includes one or more children.
- This option only accounts for one specific case and ignores the others where more than one child might develop cavities.

**Option D:** \( 1 - P(X = 0) \)
- This is the complement of the probability that none of the children develop cavities.
- Since \( P(X \geq 1) = 1 - P(X = 0) \) for binomial distributions, this correctly represents the probability that at least one child develops cavities.
- This matches the requirement of the problem.

Hence, **Option D** is the correct representation.

**Answer:** D
D
deepseekv3 The question asks for the probability that **at least one** of the five children will develop a cavity before turning 10. The correct approach is to calculate the complement of the probability that **none** of the children develop a cavity.

The complement of "at least one" is "none," so the probability of "at least one" is:

\[
P(\text{at least one}) = 1 - P(\text{none})
\]

Here, \( P(\text{none}) \) is the probability that **none** of the five children develop cavities, which is \( P(X = 0) \).

Thus, the correct answer is:

\[
1 - P(X = 0)
\]

The correct choice is **D**.
D