A data set has a mean of 100 and a standard deviation of 20. What is the probability of picking a data item that is between 60 and 120?

Question

answer choices:

a) 0.3413

b) 0.6000

c) 0.6826

d) 0.8185

Answer 1

d) is correct 0.8185

use the empirical rule

68-95-99 for 1,2 and 3 standard deviations from the mean

one half of 68+95 = (1/2)(68+95) = about 34+48 = close to 82% = 0.82

use z tables if you want more accuracy down to 4 decimal places