If the probability that at least one person makes an A on the final exam is 0.15, then the?

Question

probability no one makes an A is?

a. 0.15
b. 0.65
c. 0.85
d. 0

Answer 1

0.85

If the prob. of at least one A is 0.15, then just subtract 0.15 from 1 to get the prob that there are 0 A's.

Answer 2

the probabilty of at least one person makes an A is the 1 subtract the probablity of NO one makes a A

P(at least 1 peson) = 1 - P(no one)

.15 = 1 - P(no one)
P(no one) = .85

Answer 3

c

pr (1+ make an A) = 0.15

pr ( no As) = 1 - 0.15

hence C