On average, the bottle-nosed dolphin comes up for air once

\(30*24-12*24/12*24=30-12/12=18/12\)
So 150%, Answer is C.

Thanks guys. The OA is indeed C.

Thanks for the word translation help Bunuel. I just wanted to make sure I am interpreting wording correctly (I keep confusing myself unfortunately!).

On average, the bottle-nosed dolphin comes up for air once every two minutes; the beluga whale, a close relative, comes up for air on average once every five minutes. The number of times a bottle-nosed dolphin would come up for air in a 24 hour period is approximately what percent greater than the number of times a beluga whale would come up for air in that same period?

A) 50%
B) 100%
C) 150%
D) 200%
E) 250%

This question asks for the percentage change, but I don't see what forumulation asks that in the question? I don't see which words indicate that not the percentage of bottle-nosen dolphins to beluga whales is looked for. Could anybody help me with the formulation in these kinds of problems, I sometimes get these problems wrong because I misunderstand what's looked for in the question.

These percentage questions confused me too at a point, but the formula is pretty simple: x = y(1+P) where x is your first item (number of times dolphin comes up), y is your second item (number of times whale comes up), and p is your percentage chain.

If I ever forget the formula, what I do is use the simple fact that I 3 is 50% greater than 2, or 2 is 100% greater than 1. That way I don't confuse which number goes where

3=2(1+.5)

But anyways, back to the problem: x = y(1+P)
x = once every two minutes, or 5 times every ten minutes
y = one every five minutes, or 2 times every ten minutes

5 = 2(1+P)
P = 1.5 = 150% so the answer is C.

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