ayakik wrote:
KarishmaB This may be a very rudimentary question, and if so, I apologize in advance... But I originally got this wrong because I did 0.15*0.15 and got 0.0225, which clearly doesn't make sense. Can you please explain why this approach is incorrect? Is it because we have to take 15% of the resulting figure, not 15% of the 15% (which results in too small of a fraction)?
15% of a number is a small part of it.
For example, 15% of 100 is just 15.
But when we "increase a number by 15%" we are making it larger.
We say this is 100 + 15/100 of 100 = 115
So when we want to "increase" a number by 15%, we multiply it by (1 + 15/100) i.e. by 115/100. The number increases.
When we want to further increase it by 15%, we multiply it by another 115/100.
So we get N * 115/100 * 115/100 as the new number which is greater than the original. number N.
When we take N * 15/100 * 15/100, we are effectively finding the 15% of the 15% of the number. So if the number is 100, 15% of its 15% becomes
15/100 * 15/100 * 100 = 2.25
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