Question

I really don't get this problem

Answer 1

Convert each fraction in decimal, all of them mixed fractions, they have a integer part and other is a fraction.
For converting a miexd fraction you have to add the integer + the fraction, for example 2 7/8 = 2+7/8= (applying adding fractions of different denominator) 2.875.
So if you solve all of the mixed fraction you will get the answer is "A"

Answer 2

I haven't learned about diameter yet but I think you have to convert 2.86 and 2.94 into fractions and then see if any of those choices are in between those.