Question

Emi computes the mean and variance for the population data set 87, 46, 90, 78, and 89. She finds the mean is 78. Her steps for finding the variance are shown below. mc008-1.jpg What is the first error she made in computing the variance? Emi failed to find the difference of 89 - 78 correctly. Emi divided by N - 1 instead of N. Emi evaluated (46 - 78)2 as -(32)2. Emi forgot to take the square root of -135.6.

Answer 1

Well let’s find the actually mean

First we add up all the numbers

87+46+90+78+89 = 390

Next we divide 390 by how many numbers there are.

390/5 = 78

Therefore the mean is 78

Emi failed to find the difference

Answer 2

It's C. Emi evaluated (46 - 78)2 as -(32)2.