Question

6. (2 pts) The weights of 8-week-old French Bulldog puppies follow a normal distribution. What percent of puppies weigh more than 2.35 standard deviations below the mean?

7. (4 pts) If a Chevy Trailblazer lasts for an average of 170,000 miles and a standard deviation of 25,000 miles, assuming mileage follows a normal distribution, what is the probability that the Trailblazer will last at least 180,000 miles?

Answer 1

6)

P(z > -2.35) = 1 - P(z < -2.35) = 0.9906

Answer = 99.06%

7)

P(x 180000) = 1 - P(x   180000)

   = 1 -  P[(x - ) / (180000 - 170000) / 25000]

= 1 -  P(z 0.4)  

= 0.3446