S.chand publication New Learning Composite mathematics solution of class 7 Chapter 8 Percentage and Its Applications Exercise 8C

 Exercise 8C

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Q1 | Ex-8C |Class 7 |S.Chand | New Learning Composite maths |Percentage and Its Applications |Ch-7 |myhelper

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Question 1

What percentage is:

(a) 7 of 70?

Sol :

$=\left(\frac{7}{70}\times 100\right)$%

=10 %

(b) 8 of 32?

Sol :

$=\left(\frac{8}{32}\times 100\right)$%

=25%

(c) 19 of 25?

Sol :

$=\left(\frac{19}{25}\times 100\right)$%

=76%

(d) 117 of 650?

Sol :

$=\left(\frac{117}{650}\times 100\right)$%

=18%

(e) 180 of 300?

Sol :

$=\left(\frac{180}{300}\times 100\right)$%

=60%

(f) 850 of 3400?

Sol :

$=\left(\frac{850}{3400}\times 100\right)$%

=25%

(g) 780 of 1950?

Sol :

$=\left(\frac{780}{1450}\times 100\right)$%

=40%

(h) 27 of 9?

Sol :

$=\left(\frac{27}{9}\times 100\right)$%

=300%

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Q2 | Ex-8C |Class 7 |S.Chand | New Learning Composite maths |Percentage and Its Applications |Ch-7 |myhelper

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Question 2

What percent is:

(a) 40 paise of Rs. 8

Sol :

∴$\left(\frac{40}{800}\times 100\right)$%

=5%

(b) Rs. 5.10 of Rs. 6?

Sol :

$=\left(\frac{5.10}{6}\times 100\right)$%

$=\left(\frac{510}{6\times 100}\times 1000\right)$%

=85%

(c) 400 ml of 1 L?

Sol :

∴$\left(\frac{400}{1000}\times 100\right)$%

=40%

(d) 8.24 cm of 8 m?

Sol :

$\left(\frac{8.24}{800}\times 100\right)$% [8m=800cm]

$=\left(\frac{824}{800\times 100}\times 100\right)$%

=1.03%

(e) 6 s of 10 min?

Sol :

∴$\left(\frac{6}{600}\times 100\right)$%

=1%

(f) 18 h of 1 day?

Sol :

∴$\left(\frac{18}{24}\times 100\right)$%

=75%

(g) 900 kg of 1.5 tonne?

Sol :

∴$\left(\frac{900}{1500}\times 100\right)$ [1.5 tonne=1500 kg]

=60%

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Q3 | Ex-8C |Class 7 |S.Chand | New Learning Composite maths |Percentage and Its Applications |Ch-7 |myhelper

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Question 3

18 karat gold is a mixture of gold and another metal. 18 out of 24 parts are pure gold. Express the pure gold as a percentage of the the total.

Sol :

∴Percentage of pure gold in the mixture$=\left(\frac{18}{24}\times 100\right)$%

=75%

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Q4 | Ex-8C |Class 7 |S.Chand | New Learning Composite maths |Percentage and Its Applications |Ch-7 |myhelper

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Question 4

A CD ROM has 700 megabytes of storage space. What per cent of the space is used by a file, that take up 154 megabytes?

Sol :

∴Percentage of space$=\left(\frac{154}{700}\times 100\right)$%

=22%

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Q5 | Ex-8C |Class 7 |S.Chand | New Learning Composite maths |Percentage and Its Applications |Ch-7 |myhelper

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Question 5

As per 2011 census, the population of Sikkim is 6,10,577 of which 3,23,070 are males. What percent of the total population of Sikkim are females? [You may use calculator for calculations].

Sol :

∴Percentage of females of total population

$=\left(\frac{610577-323070}{610577}\times 100\right)$%

$=\frac{287507}{610577}\times 100$%

=47.08

≃47.1