Question: Some Percent of Something

Comment on Some Percent of Something


I'm not clear why if you plugged in values for x and y. Let's say 4 and 5 then you wouldn’t end up with different values for column A and column B.

greenlight-admin's picture

Hi Kankinza,

QUANTITY A: x percent of y
QUANTITY B: y percent of x

If we let x = 4 and y = 5 (as you suggest), we get the following:
QUANTITY A: 4% of 5
QUANTITY B: 5% of 4

Rewrite as:
QUANTITY A: (4/100)(5)
QUANTITY B: (5/100)(4)

QUANTITY A: 20/100
QUANTITY B: 20/100

The two quantities are equal.

In fact, if we plug in ANY values for x and y, we'll find that the two quantities are always equal.

Does that help?


Can we assume this as a rule? x% of y is always y% of x?
greenlight-admin's picture

Yes, we can even prove it.

x% of y = (x/100)(y) = xy/100
y% of x = (y/100)(x) = xy/100


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