RS Aggarwal solution class 8 chapter 9 Percentage Exercise 9B

Exercise 9B

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Q1 | Ex-9B | Class 8 | RS AGGARWAL | chapter 9 | Percentage

Question 1:

Tick (✓) the correct answer:
35=?
(a) 30%
(b) 40%
(c) 45%
(d) 60%

Answer 1:

(d) 60%

35=35×100%     =60%


Q2 | Ex-9B | Class 8 | RS AGGARWAL | chapter 9 | Percentage

Question 2:

Tick (✓) the correct answer:
0.8% when expressed as a decimal, is
(a) 0.08
(b) 0.008
(c) 8
(d) 0.8

Answer 2:

(b) 0.008
0.8%=0.8100          =0.008


Q3 | Ex-9B | Class 8 | RS AGGARWAL | chapter 9 | Percentage

Question 3:

Tick (✓) the correct answer:
6 : 5 when expressed as a percentage, is
(a) 8313%
(b) 90%
(c) 120%
(d) 6.5%

Answer 3:

(c) 120%
6:5=65      =65×100%      =120%


Q4 | Ex-9B | Class 8 | RS AGGARWAL | chapter 9 | Percentage

Question 4:

Tick (✓) the correct answer:
5% of a number is 9. The number is
(a) 45
(b) 90
(c) 135
(d) 180

Answer 4:

(d) 180

Let x be the required number. Then, we have:5% of x=9x×5100=95x100=9x=9×1005x=180


Q5 | Ex-9B | Class 8 | RS AGGARWAL | chapter 9 | Percentage

Question 5:

Tick (✓) the correct answer:
What per cent of 90 is 120?
(a) 75%
(b) 3313%
(c) 13313%
(d) none of these

Answer 5:

(c) 13313%
Required percentage =12090×100%                                    =13313%


Q6 | Ex-9B | Class 8 | RS AGGARWAL | chapter 9 | Percentage

Question 6:

Tick (✓) the correct answer:
What per cent of 10 kg is 250 g?
(a) 25%
(b) 5%
(c) 10%
(d) 2.5%

Answer 6:

(d) 2.5%

Required percentage=25010×1000×100%=2.5%


Q7 | Ex-9B | Class 8 | RS AGGARWAL | chapter 9 | Percentage

Question 7:

Tick (✓) the correct answer:
40% of ? = 240
(a) 60
(b) 600
(c) 6000
(d) 960

Answer 7:

(b) 600

Let the required number be x. Then, we have:40% of x=240x×40100=24040x100=240x=240×10040x=600


Q8 | Ex-9B | Class 8 | RS AGGARWAL | chapter 9 | Percentage

Question 8:

Tick (✓) the correct answer:
?% of 400 = 60
(a) 6
(b) 12
(c) 15
(d) 20

Answer 8:

(c) 15

Let the required number be x. Then, we have:x% of 400=60400×x100=60400x100=604x=60x=604x=15


Q9 | Ex-9B | Class 8 | RS AGGARWAL | chapter 9 | Percentage

Question 9:

Tick (✓) the correct answer:
(180% of ?) ÷ 2 = 504
(a) 400
(b) 480
(c) 600
(d) 560

Answer 9:

(d) 560

Let the required number be x. Then, we have:180% of x÷2=504

x×180100÷2=504

180x100÷2=504

180x100×12=504

9x10=504

x=504×109

x=560


Q10 | Ex-9B | Class 8 | RS AGGARWAL | chapter 9 | Percentage

Question 10:

Tick (✓) the correct answer:
20% of Rs 800 = ?
(a) Rs 160
(b) Rs 16
(c) Rs 1600
(d) none of these

Answer 10:

(a) Rs 160
20% of Rs 800

=Rs 800×20100
                     

=Rs 160


Q11 | Ex-9B | Class 8 | RS AGGARWAL | chapter 9 | Percentage

Question 11:

Tick (✓) the correct answer:
In an examination, Nitin gets 98 marks. This amounts to 56% of the maximum marks. What are the maximum marks?
(a) 75
(b) 150
(c) 175
(d) 225

Answer 11:

(c) 175

Let the maximum marks be x. Then, we have:56% of x=x×56100
            =56x100
Now, 56x100=98

x=98×10056

x=175


Q12 | Ex-9B | Class 8 | RS AGGARWAL | chapter 9 | Percentage

Question 12:

Tick (✓) the correct answer:
A number is first increased by 10% and then reduced by 10%. The number
(a) does not change
(b) decrease by 1 %
(c) increases by 1 %
(d) none of these

Answer 12:

(b) decrease by 1 %

Let x be the number.

A 10% increase will give a new number, 110100x = 1110x

The number is then reduced by 10%.

The new number will be 901001110x=9901000x=99100x

Difference = x - 99100x=1100x

Percentage of decrease = 1100x × 1x×100  = 1%


Q13 | Ex-9B | Class 8 | RS AGGARWAL | chapter 9 | Percentage

Question 13:

Tick (✓) the correct answer:
A period of 4 hours 30 min is what per cent of a day?
(a) 1834%
(b) 20%
(c) 1623%
(d) 19%

Answer 13:

(a) 1834%

4 h 30 min=4×60×60+30×60
               =16200 sec
24 h=24×60×60
      =86400 sec
Now, 1620086400×100%=1834%


Q14 | Ex-9B | Class 8 | RS AGGARWAL | chapter 9 | Percentage

Question 14:

Tick (✓) the correct answer:
In an examination, 65% of the total examinees passed. If the number of failures is 420, the total number of examinees is
(a) 500
(b) 1000
(c) 1200
(d) 1625

Answer 14:

(c) 1200

Let x be the total number of examineesPercentage of the examinees passed=65%Percentage of the examinees failed=35%Number of the examinees failed=35% of x
                                 =x×35100=35x100
Now, 35x100=420x=420×10035x=1200

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Q15 | Ex-9B | Class 8 | RS AGGARWAL | chapter 9 | Percentage

Question 15:

Tick (✓) the correct answer:
A number exceeds 20% of itself by 40. The number is
(a) 50
(b) 60
(c) 80
(d) 320

Answer 15:

(a) 50

Let x be the required number. Then, we have: 20% of x+40=xx×20100+40=x20x100+40=x20x100-x=-40-80x100=-40x=40×10080x=50


Q16 | Ex-9B | Class 8 | RS AGGARWAL | chapter 9 | Percentage

Question 16:

Tick (✓) the correct answer:
A number decreased by 2712% gives 87. The number is
(a) 58
(b) 110
(c) 120
(d) 135

Answer 16:

(c) 120

Let the required number be x. Then, we have:    x-2712% of x=87x-552% of x=87x-x×552×1100=87x-11x40=8729x40=87x=87×4029x=120


Q17 | Ex-9B | Class 8 | RS AGGARWAL | chapter 9 | Percentage

Question 17:

Tick (✓) the correct answer:
0.05 is what per cent of 20?
(a) 25%
(b) 2.5%
(c) 0.25%
(d) 0.025%

Answer 17:

(c) 0.25%
Required percentage=0.0520×100%=0.25%


Q18 | Ex-9B | Class 8 | RS AGGARWAL | chapter 9 | Percentage

Question 18:

Tick (✓) the correct answer:
One-third of 1206 is what per cent of 134?
(a) 3%
(b) 30%
(c) 20%
(d) 300%

Answer 18:

(d) 300%

Required percentage=12063×1134×100%=300%


Q19 | Ex-9B | Class 8 | RS AGGARWAL | chapter 9 | Percentage

Question 19:

Tick (✓) the correct answer:
x% of y is y% of?
(a) x
(b) 100x
(c) x100
(d) y100

Answer 19:

(a) x

Let the required number be z. Then, we have:x% of y=y% of zy×x100=z×y100yx100=zy100z=yx100×100yz= x


Q20 | Ex-9B | Class 8 | RS AGGARWAL | chapter 9 | Percentage

Question 20:

Tick (✓) the correct answer:
What per cent of 27 is 135?
(a) 2.5%
(b) 10%
(c) 20%
(d) 25%

Answer 20:

(a) x
Required percentage=135×72×100%=10%

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