Question

An investigator compares the durability of two different compounds used in the manufacture of a certain automobile brake lining. A sample of 259259brakes using Compound 1 yields an average brake life of 47,112 miles. A sample of 218 brakes using Compound 2 yields an average brake life of 30,86430,864 miles. Assume the standard deviation of brake life is known to be 16811681 miles for brakes made with Compound 1 and 1627 miles for brakes made with Compound 2.  Determine the 98%98% confidence interval for the true difference between average lifetimes for brakes using Compound 1and brakes using Compound 2.

Step 1 of 2:

Find the critical value that should be used in constructing the confidence interval.

Step 2 of 2:

Construct the 98%98% confidence interval. Round your answers to the nearest whole number.

upper and lower level

Answer 1

X, , 7112 63 130B64 72- 1627 7 O,시흥 2.33 1 812 62- 25 0 21 12142-79 151.83 2305 3 06 SE 15183 (HT12 -304)2-33 x 15183 IG248 ± 353.194 15894.236 , 16601.764 5394 6602