117 is the correct answer. Hope this helps!
To solve for the surface area of a sphere, the formula is 4*pi*r^2. Since we are using 3.14 instead of pi, the formula becomes 4*3.14*r^2. To solve, all we have to do is substitute in the radius for r and solve it like a normal question.
SA=4*3.14*r^2
SA=4*3.14*6^2
SA=452.16
Since we used 3.14 instead of pi, we have to say this is an approximate answer. This means the surface area of this sphere is 452.16 square inches.
(a) 
since 13 is prime.
(b) 
, and there are 81/3 = 27 multiples of 3 between 1 and 81, which leaves 81 - 27 = 54 numbers between 1 and 81 that are coprime to 81, so 
.
(c) 
; there are 50 multiples of 2, and 20 multiples of 5, between 1 and 100; 10 of these are counted twice (the multiples of 2*5=10), so a total of 50 + 20 - 10 = 60 distinct numbers not coprime to 100, leaving us with 
.
(d) 
; there are 51 multiples of 2, 34 multiples of 3, and 6 multiples of 17, between 1 and 102. Among these, we double-count 17 multiples of 2*3=6, 3 multiples of 2*17=34, and 2 multiples of 3*17=51; we also triple-count 1 number, 2*3*17=102. There are then 51 + 34 + 6 - (17 + 3 + 2) + 1 = 70 numbers between 1 and 102 that are not coprime to 102, and so 
.
I think the answer is a: 5:6
