about bio s07 mj p5 question 1

[camwell]

In the 1(a)(iv), the question have been ask what the standard deviation tells you about this investigation. the mean is 5.42, and the standard deviation is 1.15.
If we do it according to the book ,then the answer is 5.42+- (1.15 x 2) which is 5.42+-2.30. but the mark scheme saids the answer is 5.42+-1.15.
cam somebody help me out???
PLz.....................

 

[mdaniyal]

seriously sumone answer it s vexing em e!

 

[ILLmatic]

You're supposed to write mean +/- deviation

So x +/- s

 

[camwell]

it makes sense, but why?