Expert: Josh - 2/18/2004

Question
Hello:

Are there any situations that would require using the following calculations?


(1) 4/5%  (4 divided by 5%)

(2) 5%/4  (5% divided by 4)

(3) 4%/5% (4% divided by 5%)


I thank you for your assistance and for any explanations provided for (1), (2), and (3).

Answer
Hello,

(1) If you were told that 5% of X is 4, then, you can deduce X. You need to calculate 4/0.05, this is the proper expression.

As a general rule, percentages should not be included in any formal expression. I encourage you not to use "4/(5%)" in maths. You will not see this, unless you are reading a column in the Financial Review or The Bulletin or something. Then, 4/5 % would be translated to four fifths of a percentage point.

(2) We have seen this before, refer to previous discussion. (cf. interest rate at 5% p.a., compounded quarterly.)
Much better off expressing this as 0.05/4.

(3) Not very common.
Much better off writing 0.04/0.05.
Similar interpretation to (1).

4%*5% is more common. This may arise in probability calculations, when you want two events- which carry different probabilities- to occur at the same time.