Question

Mrs. Gomes found that 40% of students at her high school take chemistry. She randomly surveys 12 students. What is the probability that exactly 4 students have taken chemistry? Round the answer to the nearest thousandth.

Answer 1

C.) 0.213

Explanation:

Took the test on Ed.

Answer 2

0.213

Explanation:

This is a probability question.

Let c = probability of a student taking chemistry. That is 40% = 4/10

Now, let d be the probability of a student not taking chemistry, that would be 60% = 6/10

Now out of 12 sampled, we want to calculate the probability that exactly 4 have taken chemistry.

The easiest approach here is by the use of bernoulli approximation.

Thus,

P(x = 4) = 12C4 * c^4 * d^8

P(x =4) = 12C4 * (0.4)^4 * (0.6)^8

P(x = 4) = 495 * 0.0256 * 0.01679616

P(x = 4) = 0.2128

To the nearest thousandth, the probability is 0.213