00:01
In this problem, we are taking a sample of 55 bridges.
00:05
We are finding their mean and standard deviation.
00:08
We found that mean to be 2 ,500, and the standard deviation of the sample was 1 ,540.
00:17
We're comparing that to 1992 bridge cost, which is $25 ,03.
00:25
We're going to write a null and alternative and run our test statistic to compare the means.
00:31
The null hypothesis is that it's the same.
00:36
The bridge cost is the same as it was in 1992.
00:41
Our alternative, we're just going to say it's different.
00:45
It's not the same.
00:48
So we're running a two -tail test to say that it's different than 92.
00:56
Now we can use the formula for our t to find our t score in this problem.
01:03
To find our t score, x bar, minus the mean of 1992, divided by our sample standard deviation times the square root of n, which we know is 55...