Question

In a test of braking​ performance, a tire manufacturer measured the stopping distance for one of its tire models. On a test​ track, 10 different cars made stops from a speed of 100 km per hour. The company recorded the stopping distance for each car on both wet and dry pavement. Results are shown in the table. Complete parts​ a) and​ b).

Car #   Dry   Wet
1   47   63
2   45   67
3   42   58
4   41   61
5   40   56
6   41   52
7   40   60
8   37   53
9   40   57
10   47   62

​a) Write a​ 95% confidence interval for the mean dry pavement stopping distance. Be sure to check the appropriate assumptions and​ conditions, and explain what your interval means.

The confidence interval is ( _ , _ ).

(Round to one decimal place as​ needed.)

​b) Write a​ 95% confidence interval for the mean increase in stopping distance due to wet pavement. Be sure to check the appropriate assumptions and​ conditions, and explain what your interval means.

The confidence interval is ( _ , _ ).

​(Round to one decimal place as​ needed.)

Answer 1