Question

The mean and standard deviation of a normal distribution are 150 and 12 respectively. What percentage of values lie between:

a) 138 and 162
b) 126 and 174
c) 126 and 162
d) 162 and 174​

Answer 1

The answer would be d

Answer 2

Explanation:

Use a calculator with built-in statistical functions. The function applying here is normcdf(, the "cumulative density function."

(a) The percentage of values lying between 138 and 162 is

norm(138,162, 150, 12), which comes out to 0.683, or 68.3%.

(b) Find norm(126, 174, 150,12): 0.945, or 94.5%

(c) Find norm(126,162, 150,12); 0.819, or 81.9%

(d) Find norm(162, 174,150,12): 0.136, or 13.6%