Downloading times at a website is assumed to be uniformly di

Downloading times at a website is assumed to be uniformly distributed between 4.5 to 9.5 seconds.

1. What is the probability that download time will take 9 to 13 seconds?

2.

Product A has sold a mean of 27 items each day with a standard deviation of 5.4. Product B has sold a mean of 35 items with a standard deviation of 6.5. Which product has been more consistent in sales?

a. Sales of Product A has been more consistent

b. Sales of Product B has been more consistent

c. Sales of both products are equally consistent

d. Cannot be determined

explain asnwers

Solution

1.

PDF of Uniform Distribution f(x) = 1 / ( b - a ) for a < x < b
b = Maximum Value
a = Minimum Value
Mean = a + b / 2
Standard Deviation = Sqrt ( ( b - a ) ^ 2 / 12 )

f(x) = 1/(b-a) = 1 / (9.5-4.5) = 1 / 5 = 0.2
Mean = a + b / 2 = 7
Standard Deviation = Sqrt ( ( b - a ) ^ 2 / 12 ) = 1.443

P(9 < X < 13) = (13-9) * f(x)
= 4*0.2
= 0.8