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Hi good morning,
In the Kaplan exam kit came across a question related to standard deviation that I cannot get correct. In the answers the book uses a different method than the one we are taught (finding average, finding the difference, squaring that difference and finding the average) so I cannot compare to find out what I’m doing wrong..
The following shows the number of orders placed by the customers in the last period
No. of orders
1
2
3
4
5Frequency
3
5
10
14
8What is the standard deviation of the above data?
Appreciate your help in solving this!
As a starting point, am I correct in saying 3.475 is the average (Step 1)?Thanks,
SaraYes, you are correct in saying that the average is 3.475.
I do not know what Kaplan has done, but if you follow the same steps as in my lecture you will come to the correct standard deviation 🙂
Yes I am following the video but still cannot understand what I’m doing wrong.
If the average is 3.475, the next step is to do x – average x
1 – 3.475 = -2.475
2 – 3.475 = -1.475
3 – 3.475 = -0.475
4 – 3.475 = 0.525
5 – 3.475 = 1.525Next step is to square so (answers in order);
6.13
2.18
0.23
0.28
2.33The sum of all this is 11.13
11.13/40 = 0.28
Square root of 0.28 = 0.53
Do you agree with my answer 0.53 please?
Appreciate your helpThanks,
Sara
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