hugomimihu

I agree.

I don't know who gave you a demerit but you certainly did deserve a upvote. Please give yourself a merit point. I have added one as well.

The formula for circle are is πr^2. You have 100/360 = 50/180 = 5/18 part of the area. 

5/18 * πr^2 = 250π

5πr^2/ 18 = 250 π

5r^2/18 = 250

5r^2  = 250 * 18

r^2 =250*18/5 = 50*18 = 900

r = 30

If you don't understand anything feel free to ask!

Didn't Guest already provide a hint?

Volume of a cube is side s^3.

thus (0.6s)^3 = 0.216 * s^3.

Thus we have 216/1000 = 21.6% remaining so 78.4% decreased.

I think.

Or.

10cm/side.

1000 cm^3.

6^3 = 216.

Yup.

If you don't understand anything feel free to ask.

Hi. If you'll be so kind as to fix your latex or fill in the numbers in the blank spots. 

Since this is copied latex and the site requires you to manually input latex the latex is hidden.

Please tell me the numbers in the blanks in order for us to help you!

Hey look in case the teacher was playing a prank I wanted to make it clear that I am in no way liable LOL.

Since There are 5 people getting an A in 35, 5/35 = 1/7

You can calculate decimal yourself.

Note that this may be incorrect. From a mathmatical point of view, no, but in real life, yes.

Grades are too hard to calculate. THere are WAY too much variables.

A einstein kid could be depressed and get a D.

A idiotic kid could have bribed a teacher and gotten an A.

Thus you must note that this is theoretical probability based on information given, and strictly this. This probability can change year to year, trimester to trimester, or even day to day! 

A straight A kid can flunk a test and get a F since his friend betrayed him.

You never know.

Hi. I have offered a hint on another thread containing the same question. It should be very helpful.

As this is an AoPS question I will disclose a hint.

use the center. Use approximation to guess. It might take a try or two.