Figure the Percent

[decaine97]

1) What percent of 75 is 15?
2) 510 is 85% of what number?
3) 22 is what percent 50?
4) 45% of what number is 9?

 

[Loren]

1) What percent of 75 is 15?
2) 510 is 85% of what number?
3) 22 is what percent 50?
4) 45% of what number is 9?

"Of" means "multiply" and "is" means "equals".
In each case, you can rewrite so that the statement has only a multiplication symbol, an equal sign, a blank space and numbers. Then you can figure out what number has to go into the blank spot.

For instance, if the problem reads "30 is 75% of what number?" you can change it to read...
30 = 75% X ___

Now, you can apply whatever method your teacher or book has shown you. There are several different approaches to getting the answer, but they all boil down to changing the % to either a fraction or a decimal, then figuring out what has to be in the blank spot. Your thinking my go something like this... 75% is the same as 0.75. If I multiply 0.75 times some number and get 30, then 30 divided by 0.75 gives me the number I'm after. So you divide 30 by 0.75 and get 40. I think my answer is 40. To be sure, I check it by going back to the original statement and plug 40 in place of what number. It reads 30 is 75% of 40. Is this correct? I know that of means multiply so I multiply 40 by 75%. Lo and behold, I get 30, so my answer of 40 is correct.
All the problems you have presented are variations of this. If you need more help, show us your work on each problem so we can see how to help.

 

[Deleted member 4993]

1) What percent of 75 is 15?
2) 510 is 85% of what number?
3) 22 is what percent 50?
4) 45% of what number is 9?

for a quick review go to:

http://www.purplemath.com/modules/percents.htm

Please show us your work, indicating exactly where you are stuck - so that we know where to begin to help you.