Problem Solving

Hi
I am stucked in one question while writing test of GMAT Prep.

Please resolve the same with explanation.

Thanks
Nikhil[/img]

I will go for D

My approach is

there are total 6 number within 1 std dev. of the mean
= 10 -(0.3)*1= 9.7
and
= 10 +(0.3)*1 = 10.3

so
x/100 *8=6
Ans = 75%
Let me i know if i am correct
Thanks

Ya i too get the same: SD= 0.3 and Mean = 10.0

-------------------- +1 SD = 10.3

-------------------- Mean = 10.0

-------------------- -1 SD = 9.7

The following numbers are within this range from 9.7 to 10.3. They are:
9.9,9.9,9.9,10.0,10.0,10.2 = 6 numbers.

So 6/8 *100 = 75%=D.)

-Deepak

Thanks Deepak and gurav....I got the solution....If you have any theory or notes related to standard deviation...then could you please provide them

Thanks
Nikhil