Page 120 - ICSE Math 6

Alternatively, number of red pens = (100 – 40)% of 110 = 60% of 110
60
= × 110 = 66
100

Example 3: A man spends 20% of his salary on shopping and 25% on food. How much money does
he save if his salary is ` 50,000?
Solution: Money spent on shopping = 20% of ` 50,000

 20 
= `  ×50,000 = ` 10,000

 100 
Money spent on food = 25% of ` 50,000

 25 
= `  ×50,000 = ` 12,500

 100 
Money saved = ` 50,000 – ` 10,000 – ` 12,500 = ` 27,500

Alternatively, money saved = (100 – 20 – 25)% of ` 50,000
= 55% of ` 50,000
 55 

= `  ×50,000 = ` 27,500
 100 
Example 4: Out of 60 students in a class, 25% students got the first division in the annual examination,
45% students got the second division and the remaining students just passed. Find the
number of students who just passed.
25
Solution: Number of students who got the first division = 25% of 60 = ×60 = 15
100
45
Number of students who got the second division = 45% of 60 = ×60 = 27
100
\ Number of students who just passed = (60 – 15 – 27) = 18
Alternatively, number of students who just passed = (100 – 25 – 45)% of 60

30
= 30% of 60 = ×60 = 18
100
Finding the Number from its Given Percentage
Write the given percentage as a fraction with the denominator 100 and then divide the given number
by this fraction to get the required number.

Example 5: If 25% of a number is 25, find the number.

 25  25 ×100
Solution: Required number = 25 ÷   = = 100
 100  25
1
Example 6: If 13 % of a number is 54, find the number.
2
1 27 27
Solution: Since 13 % = % =
2 2 2 × 100

\ Required number = 54 ÷   27   = 54×2×100 = 400
 2×100  27

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