The first question is relatively harder
So let’s start with that
Area of circle is 3.14(r^2)
We are given the diameter as 20m
So radius is 10m
Thus area = 3.14(100)= 314 sq metres
Now each box covers 58 sq metre
So no of boxes = 314/58= 5.41
Rounding to 1 significant figure
It’s 5 boxes
Clearly we are underestimating it as it’s around 5 boxes and a half
For the second question just equate their area
(11)(10)/2 = 22b
=> b= 2.5cm