Question

In a study of facial behavior, people in a control group are timed for eye contact in a 5- minute period. Their times are normally distributed with a mean of 184 seconds and a standard deviation of 55 seconds. For a randomly selected person from the control group, find the probability that the eye contact time is greater than 230 seconds

Answer 1

0.20148

Explanation:

We solve using z score formula

z = (x-μ)/σ, where

x is the raw score = 230

μ is the population mean = 184

σ is the population standard deviation = 55

z = 230 - 184/55

z = 0.83636

P-value from Z-Table:

P(x<230) = 0.79852

P(x>230) = 1 - P(x<230) = 0.20148

Therefore, the probability that the eye contact time is greater than 230 seconds is 0.20148