smartguy595 wrote:
boomtangboy wrote:
Hi
In order to solve this problem we need to know the mean & the terms of the sample.
Statement A :
Gives us 39 consecutive even elements
Eg : 0,2,4,.....
To Compute SD
1. Compute the difference of each data point from the mean, and square the result of each
2. compute the average of these values, and take the square root
Which we can calculate easily from the given data
Thus statement A is sufficient
Statement B
Mean is 382 only gives us the mid point of the set but not the number of elements hence we cannot calculate the SD
Thus statement B is insufficient
Hope this helps
Dear Experts,
Please explain how statement A is sufficient to calculate standard deviation.
From the given information which 39 even elements we need to consider .
IMO these 39 elements can be from 0,2,4.... or from 100,102,104...
will the standard deviation calculated from any of the 'n' number of even integers is same?
Please advise
hi,
since the elments are consecutive and number of elements are same, SD will remain same..
For SD we take out AVERAGE and subtract each number from it...
two cases
1) 0,2,4....38*2
average = 19*2 = 38..
subtract ecah number 38-0 = 38 and 38-2 = 36 and so on
2) 100,102.... 100+38*2
average = 100+19*2 = 138
Difference 138-100=38 and 136-2 = 36..
so you see the difference is the same..
SD depend s on HOW far the numbers are SPREAD..
and in each case with 39 consecutive elements, the numbers are equally spread
Hope it helps
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