# NCERT Solutions for Class 8 Maths Chapter 8 Exercise 8.1

Free NCERT Solutions for Class 8 Maths Chapter 8 Exercise 8.1 (Ex. 8.1) Comparing Quantities in Hindi and English Medium to download in PDF for 2020-2021. All the contents are updated for CBSE and State board academic session 2020-21.

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Class: 8 | Mathematics |

Chapter: 8 | Comparing Quantities |

Exercise: 8.1 | PDF and Videos Solutions |

### CBSE NCERT Class 8 Maths Chapter 8 Exercise 8.1 Solution in Hindi and English Medium

### Class 8 Maths Chapter 8 Exercise 8.1 Solution in Videos

#### Per Cent:

By a certain per cent we mean that many hundredths.

We denote x per cent by x%.

x% = x hundredths = x/100

##### Express each of the following as a fraction: (i) 36%, (ii) 120%, (iii) 0.8%

(i) 36% = 36/100 = 9/25

(ii) 120% = 120/100 = 6/5

(iii) 0.8% = 0.8/100 = 8/1000 = 1/125

##### Express each of the following fractions as a percentage: (i) 7/25 (ii) 5/8 (iii) 11/6 We have

(i) 7/ 25 = (7/25) x 100% = 28%.

(ii) 5/8 = 5/8 x 100% = (125/2) %

(iii) = 11/6 x 100% =550/3 % = 183 %.

##### In a class, the girls are 60% of the total number of students and the boys are 18 in number. How many students are there in the class?

Let the total number of students in the class be x.

Percentage of girls = 60%.

Percentage of boys = 40%.

So, number of boys = 40% of x = x X 40/100 = 2x /5

2x/5 = 18, x = 18 x 5 /2 = 45

Hence, the total number of students in the class is 45.

##### The price of sugar goes up by 20%. By how much per cent must a housewife reduce her consumption of sugar so that the expenditure on sugar remains the same?

Let the consumption of sugar originally be 1 unit and let its cost be 100.

New cost of 1 unit = 120.

Now, 120 yield 1 unit of sugar.

So, Rs. 100 will yield (1/120) x 100 unit = 5/6 units of sugar.

Reduction in consumption = 1- (5/6) = 1/6 units

So, reduction % in consumption = (1/6 x 5/6 x 100) % = 50/3 %

##### Find the percentage of pure gold in 22-carat gold, if 24- carat gold is 100% pure.

22-carat gold contains 22 parts out of 24 parts. percentage of pure gold in it = (22/24) x 100 % = 91%.

##### How do I calculate a percentage between two numbers?

First: work out the difference (increase) between the two numbers you are comparing.

Increase = New Number – Original Number.

Then, divide the increase by the original number and multiply the answer by 100.

% increase = Increase ÷ Original Number × 100.

##### How do I calculate percentage of a total?

Determine the whole or total amount of what you want to find a percentage for.

Divide the number that you wish to determine the percentage for.

Multiply the value from step two by 100.