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Statistics: Mean and SD

For a data set of 41 items with ∑x = 4411.6, ∑x2 = 479697.162
the mean is to 3 dps and
the standard deviation is to 3 dps.

tickcross


Worked Solution:

The number of items is n = 41
The mean is x =
∑x
---
n
 =
4411.6
---
41
 = 107.6 = 107.600 to 3 dps.
variance = s2 =
∑x2 – n x2
---
n – 1
 =
479697.162 – 41×107.62
---
41 – 1
 = 125.225050
=> the standard deviation is s = √variance = √125.225050 = 11.190400 = 11.190 to 3 dps.

Statistics 1 (MEI Structured Mathematics S1) Third Edition (2004) pages 34-45
© MEI Produced by Dr Ron Knott, 12 December 2006
tom . button [AT] mei . org . uk 		Test reference: StatisticsMandSD.html?ref=8863