Question

Question 2 (3 points)A compact disc is designed to last an average of 4 years with a standard deviation of 0.8 years.What is the probability that a CD will last less than 3 years? (3 points)оа1.11%Ob10.56%ос86.65%Od100%

Answer 1

Data

• mean: 4 years

,

• standard deviation, sd = 0.8 years

,

• point of interest, x = 3 years

,

• z-score, z = (x - mean)/sd = (3 - 4)/0.8 = -1.25

,

•

The probability that a CD will last less than 3 years is equivalent to find P(z < -1.25). Using the attached table:

P(z < -1.25) = 0.1056 or 10.56%