Question

In a mid-size company, the distribution of the number of phone calls answered each day by each of the 12 receptionists is bell-shaped and has a mean of 64 and a standard deviation of 11. Using the empirical rule (as presented in the book), what is the approximate percentage of daily phone calls numbering between 53 and 75?

Do not enter the percent symbol.
ans =  %

Answer 1

Solution :

Given that ,

mean = = 64

standard deviation = = 11

P(53 < x < 75) = P[(53 - 64)/ 11) < (x - ) /  < (75 - 64) / 11) ]

= P(-1.00 < z < 1.00)

= P(z < 1.00) - P(z < -1.00)

Using z table,

= 0.84 - 0.16

= 0.68

Using Empirical rule,

  P( - < x <   + ) = 68