book Maths Puzzle Numerical Ability

How to find this formula
sphere: diameter = 76.4
cylinder: diameter=16.2m, h=7.5m
cone: d=9.5in, h=7in

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book Other Question

I get confused on how to diversify between putting a negative and positive on problems such as in multiplying, dividing, adding, and subtracting. How do i keep them straight? Is there some kind of way i can keep them apart or at least remember them?? (a) If we roll two fair dice, what is the probability that a total of nine shows?
(b) if we toss four fair coins, what is the probability that we get exactly two heads?