Finding a percent given a part and a whole :
For the purpose of comparison, in our day to day life, often we need to find percent for the given part and whole.
We can use the following two methods to find percent for the given part and whole.
1. Proportional reasoning
The formula to find percent using proportional reasoning is given by
The formula to find percent using multiplication is given by
Example 1 :
The school principal spent $2,000 to buy some new computer equipment. Of this money, $120 was used to buy some new keyboards. What percent of the money was spent on keyboards ?
Step 1 :
Since we want to know the part of the money spent on keyboards, compare the part to the whole.
Step 2 :
Write a proportion comparing the percent to the ratio of part to whole.
Step 3 :
Find the multiplication factor.
Since 100 · 20 = 2,000, find what number times 20 equals 120.
Step 4 :
Find the numerator.
6/100 = 120/2000
(Since 20 · 6 = 120, the percent is 6%)
Hence, the principal spent 6% of the money on keyboards.
Example 2 :
Out of the 25 students in Mrs. Green’s class, 19 have a pet. What percent of the students in Mrs. Green’s class have a pet ?
Let us use multiplication method to find percentage.
Step 1 :
In multiplication method, the formula is
Percent = (Part / Whole) x 100 % -----(1)
Step 2 :
Since we want to find percent of the students in Mrs. Green’s class have a pet, the part is 19 and the whole is 25.
Then, we have
(1)------------ > Percent = (19/25) x 100 %
Percent = 19 x 4 % = 36 %
Hence, 36 percent of the students in Mrs. Green’s class have a pet.
After having gone through the stuff given above, we hope that the students would have understood "How to find a percent given a part and a whole".
Apart from the stuff given above, if you want to know more about "Finding a percent given a part and a whole", please click here
Apart from the stuff given in this section, if you need any other stuff in math, please use our google custom search here.
APTITUDE TESTS ONLINE
ACT MATH ONLINE TEST
TRANSFORMATIONS OF FUNCTIONS
ORDER OF OPERATIONS
Different forms equations of straight lines
MATH FOR KIDS
HCF and LCM word problems
Word problems on quadratic equations
Word problems on comparing rates
Ratio and proportion word problems
Converting repeating decimals in to fractions