Angus is an expert dart tosser He hits the bullseye 85 of th

Angus is an expert dart tosser. He hits the bullseye 85% of the time. If Angus tosses 400 darts what is his corresponding z-score for 50 or fewer misses of the bullseye?

Select one:

a. 1.4

b. -1.4

c. 4.61

d. -4.61

Solution

N = 400

PROBABILITY = 0.85

expected value = .85(400) = 340

STD DEV = sqrt(.85*.15*400) = sqrt(51)

HENCE Z SCORE WILL BE = (350-340)/SQRT(51) = 1.4

OPTION A IS CORRECT.