Question

assume that a set of test scores is normally distributed with a mean of 100 and a standard devaiton of 20. Use the 68-95-99.7 rule to find the following quantities:
a. percentage of scores greater than 120

Answer 1

would the percentage of scores greater than 120 be 4.865 or 4.87

Answer 2

Z = (120-100)/20 = 20/20 = +1

Of the 50% higher than the mean, Z = +1 gives you

50 - 1/2(68) = 50 - 34 =?

Answer 3

16