30 over 12 written as a mixed number is 2 and 6/12, which is simplified to 2 and 1/2.
The pertinent formula for the circumference of a circle with diameter d is
C =pi*d.
Thus, if the dia. is 6 inches, the circumf. is C = 6pi inches. Alternatively, if we let pi = 3.14, the circumf. is C = 6*3.14 (answer A).
It would take 2 hours. To complete the whole lawn you would need:

To make a whole, so to get that we multiply:

So we use the same number required for the whole lawn, and multiply it times the hours
So we are given that the mean is 42% and the sd (standard deviation) is 8%
Assuming our data is normal we can use the 68-95-99 rule
So one thing you should realize is that 42% + 8% is 50% which is passing. That is one standard deviation higher. So we use:
100 - 68 - 13.5 - 2.35 - 0.15 = 16. That means 16% of students passed the test. Which is terrible. They probably need to hit the books more.
Anyways if you have any question feel free to message me!
Hopes this helps!
17, 21, 25, etc. because when you divided 4 by any of these numbers you will get your answer with a remainder of 1. For example, 17/4 is 4 R.1 because 4 times 4 is 16, then you will have one left over. (At my school you always go to a decimal not a remainder)