To Calculate a Number When its Percentage is Known

To calculate a number when its percentage is known are discussed here. Let us consider some of the examples on word problems on percentage.

1. Marlena scored 80% out of a total of 500 marks. How many marks did he score?

Solution:

Marlena’s marks = 80% of 500

= (80/100) × 500

= (4/5) × 500

= (4 × 500)/5

= 2000/5

= 400

Therefore, Marlena scored 400 marks.

2. In an examination, Sherry scored 89% marks out of 750 marks. How many marks did he get?

Solution:

Sherry’s marks = 89% of 750

= (89/100) × 750

= (89× 750)/100 = 66750/100 ÷ 50/50

= 1335/2

= 667.5

Therefore, Sherry scored 667.5 marks.

These are the word problems where we need to calculate a number when its percentage is known.


1. Sara got 150 questions as assignment for a week. If she did 70% of the questions in the first four days, how many questions would she have to do in the remaining days?

Solution:

Questions completed by Sara in the first 4 days = 70% of 150

= (70/100) × 150

= (7 × 150)/10

= 1050/10

= 105

Total questions = 150

Question completed = 105

Remaining questions = 150 – 105

= 45

Therefore, Sara would have to do 45 questions in the remaining days.

2. On a rainy day 35% of a class of 40 students were present. Find the number of absentees.

Solution:

Number of students present on a rainy day = 35% of 40

= (35/100) × 40

= (7/20) × 40

= (7 × 40)/20

= 280/20

= 14

Total numbers students = 40

Number of students were present on a rainy day = 14

Number of students were absentees on a rainy day = 40 – 14

= 26

Therefore, 26 students were absent.



3. Paul earns $ 24000 per month. He saves 28% of his salary. How much does he spend every month?

Solution:

Paul earn per month = $24000

Amount of money he save from his salary = 28% of 24000

= (28/100) × 24000

= (7/25) × 24000

= (7 × 24000)/25

= 168000/25

= 6720

Paul saved from his salary = $6720

Paul spend = $(24000 – 6720) = $17280

Therefore, Paul spend $17280 from his salary.



4. The population of a village is 2400. If 12% were children, find the number of adults.

Solution:

Total population in a village = 2400

Population of children in a village = 12% of 2400

= (12/100) × 2400

= (3/25) × 2400

= (3 × 2400)/25

= 7200/25

= 288

Population of adults = 2400 – 288

= 2112

Therefore, there are 2112 number of adults.

These are the different types of word problems to calculate a number when its percentage is known.

● Percentage

To Convert a Percentage into a Fraction

To Convert a Fraction into a Percentage

To find the percent of a given number

To find what Per cent is one Number of another Number

To Calculate a Number when its Percentage is Known

5th Grade Numbers Page

5th Grade Math Problems

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