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.
Q. 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.
Identify values: Identify the values of n, k, and p for the binomial probability formula. Here, n=12 (number of students surveyed), k=4 (students who have taken chemistry), and p=0.40 (probability of a student taking chemistry).
Use formula: Use the binomial probability formula: P(X=k)=C(n,k)⋅(p)k⋅(1−p)(n−k). Substitute the values: P(X=4)=C(12,4)⋅(0.40)4⋅(0.60)(12−4).
Calculate C(12,4): Calculate C(12,4), which is the number of combinations of 12 students taken 4 at a time. C(12,4)=4!×(12−4)!12!=495.