5% of 30 liters is

Answer 1

When I teach this type of problem, I like to set up a proportion. A proportion is a fraction equal to another fraction. There is a template you can follow.

is %

— = —

of 100

Now we fill in what we know based on the words in the problem.

5% of 30 liters is what?

is 5

— = —

of 100

5% of 30 liters is what?

is 5

— = —

30 100

Since we don’t know what number goes with “is” we use x.

x 5

— = —

30 100

Now, we cross multiply. So we multiply 100 times x, which is 100x. We also multiply 5 times 30, which is 150. Then we set them equal.

100x = 150

Divide both sides by 100 to get x alone.

100x 150

— = —

100 100

x = 1.5 liters

Make sure you include your unit (liters)!

I hope I was able to help. Please reach out if you’d like to arrange a tutoring session on this topic!

Answer 2

You translate it word by word into an expression with "%" = 1/100 and "of" meaning multiplication:

5 % of 30 = 5/100 of 30 = 5/100 * 30 = 0.05 * 30 = 1.5

Answer 3

Hi Munira,

If we're looking for a percentage of something, then we're looking for a part of a whole.

30 Liters is the whole in this case, and 5% (percent means per 100 literally, think 100 cents to a dollar) would therefore be the same as 5/100. If we're talking about taking a part of something, this means multiplication.

This means we have (5/100)*30.

We can either rewrite as a decimal (0.05) or simplify the fraction (1/20).

0.05*30 = 1.5 Liters!

Let me know if you have any questions.

Thanks.