Question

a study of the time spent shopping in a supermarket for a market basket of 20 specific items showed an approximately uniform distribution between 20 minutes and 40 minutes. What is the probability that the shopping time will be
a) between 25 and 30 minutes?
b) less than 35 minutes
c) what are the mean and standard deviation of the shopping time

Answer 1

If it is a uniform (not normal) distribution, the range = 40 -20 = 20

a. 5/20
b. 15/20
c. Mean = 30
(I don't know how one could determine SD in this case.)

Answer 2

wdf

Answer 3

P(X<35)= (20<X<35) =15/20
P=Varx=((b-a)^2)/12 = ((40-20)^2/12=33.333? may be