Sangeeta2018 wrote:

The highest term in a set is 3SD above the Mean. The lowest term is 4SD below the mean. If the highest term is 200 and Range is 140, find the Standard Deviation.

A. 20

B. 60

C. 140

D. 200

E. 300

Source:

Experts' GlobalLet mean be denoted as M

Highest term = M + 4SD

Lowest term = M - 3SD

Range = 140, i.e.

M + 4sd - M + 3sd = 140

7sd = 140

sd = 20;

or

M+4sd = 200 .. eq 1

Range = 140 --> 200 - Least number = 140 ==> least number = 60

M - 3sd = 60 .. eq 2

Solve for sd from eq 1 and 2; you will get 7sd = 140 and sd = 20;

Now my doubt is - where is 20 in the answer choices ??? or did I make a mistake