Question

can you answer with explanation how its answer is 0.63?? Aja's favorite cereal is running a promotion that says 1-in-4 boxes of the cereal contain a prize. Suppose that Aja is going to buy 5 boxes of this cereal, and let X represent the number of prizes she wins in these boxes. Assume that these boxes represent a random sample, and assume that prizes are independent between boxes. What is the probability that she wins at most 1 prize in the 5 boxes

Answer 1

Let n = total boxes (5)

Probability (p) = 1 out of 4 = 1/4 = 0.25

Probability she wins at most 1 out of 5 is p(x <=1) Which is also = p (x =0) + p(x=1)

Probability of not winning would be 0.75 ( 1-0.25)

No prizes in 5 boxes = 0.75^5

1 prize in 5 boxes = 5 x 0.25 x 0.75^4

Total probability = 0.75^5 + 5 x 0.25 x 0.75^4 = 0.63