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1. You are the manager for the toll booth at the George Washington Bridge. You w

ID: 3262612 • Letter: 1

Question

1. You are the manager for the toll booth at the George Washington Bridge. You want to know how long it takes for the average vehicle driver to pay the toll for experienced toll takers. You take a random sample of 25 tolls on Friday evening and find the following times (in minutes).

2.2   2.4   2.5   2.2   2.8   4.0   1.3   4.1   3.6   2.5   1.4   3.3   2.8

1.2   2.0   3.0   2.3   4.0   3.6   0.8   3.1   2.5   3.6   2.4   1.0

Calculate the confidence interval for the mean toll times at the 0.99 level.

Explanation / Answer

from above given data:

for (n-1=24 ) degree of freedom and 99% interval ; critical value of t =2.7969

therefore 99% confidence interval for the mean =sample mean -/ +t*std error =2.0495 ; 3.1185

please revert for any clraification required.

X 2.2 2.4 2.5 2.2 2.8 4 1.3 4.1 3.6 2.5 1.4 3.3 2.8 1.2 2 3 2.3 4 3.6 0.8 3.1 2.5 3.6 2.4 1 mean(X) 2.584 std deviation(S) 0.956 std error =S/(n)1/2 0.191