—
3.18 is the answer i believe !
Answer:2
Step-by-step explanation:
Given
Physics problem requires 20 min
Math problem require 10 min
suppose x question of Physics and y questions of Math are done
so according to the question

Time require for x Physics problem 
Time require for y Math problem 
so,

On solving (1) and (2)
we get
and 
Maximum no of Physics question which can be solved is 2
Answer:
50.24
Step-by-step explanation:
A= πr2
314/100×4×4=50.24
Area for circle is πr² so πr² =28.26 and we can sub 3.14 as pi
3.14*r²=28.26 we can divide by 3.14 to get r² on it's own
r²=28.26/3.14
then we root both sides to get r on it's own
28.26/3.14=9 √9=3
and the diameter is double the radius 3*2=6 so the diameter is 6