Solve example 19. Show me your work and what does it mean by bottom quartile?? A

Question

Solve example 19. Show me your work and what does it mean by bottom quartile??

A computer is used for office work at home, research, communication, personal finances, education entertainment, social networking and a myriad of other things. Suppose that the average number of hours a household personal computer is used for entertainment is 2 hours per day. Assume the times for entertainment are normally distributed and the standard deviation for the times is half an hour. a. Find the probability that a household personal computer is used between 1.8 and 2.75 hours per day. b. Find the maximum number of hours per day that the bottom quartile of households use a personal computer for entertainment.

Explanation / Answer

To find the maximum number of hours per day that the bottom quartile of households uses a personal computer for entertainment, find the 25th percentile, k, where P (x < k) = 0.25.

mean = 2 , s = 0.5

By using z standard right tail we get, z value = - 0.67

z = ( x - mean) / s

x = mean + z * s

= 2 - 0.67 * 0.5

= 1.67

The maximum number of hours per day that the bottom quartile of households uses a personal computer for entertainment is 1.67 hours.

k =

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