# Need help with question about variance

#### vanebliss

##### New Member
Hello all, this is my first post here, thanks for this opportunity.
I'm studying statistics and can't seem to solve a question.
It goes like this:

For the sequence of numbers (1, 1, 3, 4), the variance is:
(a) 1 (b) 2 (c) 2,25 (d) 2,75 (e)3

The answer is supposed to be letter (b), with the variance being 2, but I can't get to that!

Here's my calculation:

var= (1/N)* [(sum from 1 to N) (xi- average)^2]
Being N the number of elements in the population.

It takes me to this calculation:
N=4
average= (1 + 1 + 3+ 4)/N = 9/4
var=(1/4)* [(1 - (9/4))^2 + (1 - (9/4))^2 + (3 - (9/4))^2 + (4- (9/4))^2]
var=1.68, which is the wrong answer according to this material I have. Anyone can help me solve this, please?

#### vanebliss

##### New Member
Hi,

Your calculation is okay.

var =1.6875 (varaince)
S^2=2.25 (sample variance)

I checked in both:
Excel
http://www.statskingdom.com/10StandardDeviation.html

And got the same results
Thanks obh! Now I can move on. Sometimes one or another "official" answer can be wrong; perhaps a confusion on the teacher's part.