Question

Washing Hands Based on observed males using public restrooms, 85% of adult males was their hands in a public restroom. In a survey of 523 adult males, 518 reported that they wash their hands in a public restroom. Assuming that 85% observed rate is correct, find the probability that among 523 randomly selected adult males, 518 or more wash their hands in a public restroom. what do you conclude?

Answer 1

p = 0.85

q = 1 - p = 0.15

n = 523

mean = np = 523 X 0.85 = 444.55

SD = = =

To find P(X518):

Applying continuity correction:

To find P(X > 517.5):

Z = (517.5-444.55)/8.1659 = 8.9335

Table of Area Under Standard Normal Curve gives area = 0.5 nearly.

So,

P(X518) = 0.5 - 0.5 nearly = 0 nearly.

Conclusion:

Among 523 randomly selected adult males, the probability that 518 or more wash their hands in public restroom is almost zero.