121 is big enough to assume normality and not worry about the t distribution. By the 68-95-99.7 rule a 95% confidence interval includes plus or minus two standard deviations. So 95% of the cars will be in the mph range

The question is a bit vague, but it seems we're being asked for the 95% confidence interval on the average of 121 cars. The 121 is a hint of course.
The standard deviation of the average is in general the standard deviation of the individual samples divided by the square root of n:

So repeating our experiment of taking the average 121 cars over and over, we expect 95% of the averages to be in the mph range

That's probably the answer they're looking for.
1 meter = 100 centimeters, so 120 centimeters equal to 1.2 meters.
Answer:
10.
8. 
Step-by-step explanation:
10. each step is 36, so i added it twice to get 72.
then add 16 twice = 32
this gives us two sides to our triangle.
We can now use tan since we know opp and adj
tan 32/72 = .44
arctan = 23.75
8. since we again know the opposite and adjacent sides to the angle e are trying to find we can use tan again.
tan 12.5/18 = .694
arctan= 34.76