Exam 6: The Normal Distribution

Fill in the blanks by standardizing the normally distributed variable. -The amount of time that customers wait in line during peak hours at one bank is normally distributed with a mean of 14 minutes and a standard deviation of 3 minutes. The percentage of Time that the waiting time exceeds 12 minutes is equal to the area under the standard normal curve That lies to the ___ of ___.

Solve the problem. -Frequency data were reported for the ages of full-time employees at a company. The age distribution is given in the table. Obtain a relative-frequency histogram of these data and Determine whether the ages are approximately normally distributed. Age (yrs) Frequency 20 -under 25 14 25 -under 30 39 30 -under 35 99 35 -under 40 300 40 -under 45 385 45 -under 50 240 50 -under 55 87 55 -under 60 24 60 -under 65 15

Provide an appropriate response. -In assessing the normality of a data set, why is it easier to interpret a normal probability plot than it is to interpret a histogram?

A variable is normally distributed with a mean of 100 and a standard deviation of 10. Which is larger, the percentage of observations between 80 and 90 or the percentage of observations between 120 and 130? Explain your reasoning.