Please help with homework

Question

Human IQ scores are normally distributed with a mean of 100 and a standard deviation of 15. if a person is selcted at random find the probality that the iq is .

A)less than 95.

B) more than 110

C) between 81 and 112

D)find the in for the top 3 percent of the population

E)find the 90 percent percentile of iq

F) find the iq for the bottom 5 percent of the population

G) find the minimum and maximum of iqs for the middle 50 percent of H) the population now assume 10 people is selected at a random find the probability of their mean iq is

i. Less than 100

ii More than 112

iii between 103 and 115

Answer 1

The probability distribution P(x<z) is the z score calculated from the formula (x - xbar)/stdev

For P(x>z) it is 1 - P(x<z) using the calculation of a as stated above.

For the percentage problems, work backwards by converting the percent to a decimal and plugging into the respective formula from above. Solve for unknown.