Standard Deviation

CFA Level I
#1

99% of daily sales range is between $230 and $480 and daily sales are normally distributed. What is the Standard Deviation A) 83.3 B) 41.6 C)62.5

#2

B

#3

99% is 3 STD’s. take 480-230=250/6 to get 41.67 The six is because there are 3 STD’s on each side.

#4

I missed the key word “on each side” Thank you!