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Mr Cobb says that increasing something by 10% then decreasing it by 10% will just give you the original amount. Mr Pathuis says the new amount will be bigger. Mr Drake says the new amount will be smaller. Who is right and why?​

User Marcoresk
by
7.6k points

2 Answers

2 votes

Answer:

Mr Drake Is correct

Explanation:

When you increase something by 10%, you multiply the original value by 1.1. When you decrease it by 10%, you multiply the increased value by 0.9. So the final amount is:

original value x 1.1 x 0.9 = 0.99 x original value

Therefore, the new amount will be slightly smaller than the original amount, and Mr. Drake is correct.

User Siavach
by
6.7k points
3 votes

Answer:

Mr Drake is right.

Explanation:

Because you first decreased it by 10% of the ORIGINAL value.

You then increased it by 10% of the DECREASED value.

The percentages are the same percentages, but on different base amounts.

Simple example:

$100 decreased by 10% of $100 ($10) is $90.

$90 increased by 10% of $90 ($9) is $99.

User Hello Man
by
7.6k points