Typically, 10% of students make a D on their tests, 60% make a C on their test, and 30% make an A. Mrs. Smith uses a random-number table to find the experimental probability that of 5 students', at least 3 will make a C. The digit 0 represents students who make a D. The digits 1,2,3,4,5, and 6 represent students who make a C. The digits 7,8, and 9 represent students who make an A.
Find the experiment that of 5 students at least 3 will make a C.
A:7/20
B:9/20
C: 11/20
D:13/20
I would think the answer would be D because at least 60% have to make a C. Given the fractions D is the only fraction with higher than 60%.
Mathematically evaluating 3/5 is 60%, 20 is the common denominator in every answer choice. 20 is a multiple of 5, so 20/5 = 4.
Multiply 4 *3 =12
At least 12 students must have a C.
Only answer that fits is D