The Student Room Group

AS Stem and Leaf Diagram + Standard Deviation

Hi I don't know how to work out the standard deviation from this stem and leaf diagram (below), and the book says the answer is 13.7 and I have no idea how it got that. Thank you for any help.
stem and leaf question.jpg
What are the formulae for standard deviation for a (finite) discrete distribution?
What do you have to calculate before you can calculate sn_n (or sn1_{n-1})?

Clive
(edited 8 years ago)
Reply 2
Original post by cliverlong
What are the formulae for standard deviation for a (finite) discrete distribution?
What do you have to calculate before you can calculate sn_n (or sn1_{n-1})?

Clive


I don't understand what that formula is for standard deviation as I have only been taught 2 so far. I managed to work it out by squaring every single number and adding them together to get the square of x and then using the standard deviation formula I have learnt at school, and managed to get the right answer. But thank you anyway :smile:
You have gone from "I don't know how to work out" to "I have used the formula I was shown at school and obtained the right answer". Well done.
Reply 4
Original post by cliverlong
You have gone from "I don't know how to work out" to "I have used the formula I was shown at school and obtained the right answer". Well done.


Thank you :smile:
Original post by Meggy moo 11
Thank you :smile:

You did the hard work !

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