Solve these arithmetic questions on percentage

This article is in continuation to the last article focusing on the percentage topic. Here are some practice questions along with solutions that will help you in your preparation for the State government recruitment jobs.

 

1. Height of a right circular cone is decreased by 6.25% and its radius is decreased to 15 cm, the volume of a cone is decreased by 40%. Radius of a new cone is how much lesser than previous cone?

a) 3.5 cm b) 3.75 cm c) 4 cm d) 4.25 cm

Ans: b

Solution: Volume = 兀r²h
V/h = r²
V —> 5 : 3
h —> 16 : 15
r² —> 5 × 15 : 16 × 3
25 : 16
r —> 5 : 4

-1
4 —> 15cm
1 —> ?
15/4 = 3.75 cm

2. If the height of a cone is increased by 100%, then its volume is increased by?

a) 100% b) 200%
c) 300% d) 400%

Ans: a

Solution: 100% = + 100/100 = + 1/1
volume = 1/3 兀r²h
height —> 1 : 2

volume —> + 1/1 × 100%
= 100%

 

3. If the height of a right circular cone is increased by 200% and the radius of the base is reduced by 50%, the volume of the cone…

a) increases by 50%
b) increases by 25%
c) decreases by 50%
d) decreases by 25%

Ans: d

Solution: 200%
= + 200/100
= + 2/1, 50%
= -50/100 = -1/2
Volume = 1/3 兀r²h
radius —> 2 : 1
r² —> 4 : 1
height —> 1 : 3
Volume —> 4 : 3

-1/4 × 100% = -25%

 

4. The height and base radius of a cone is increased by 100%. The percentage increase in the volume of the cone is?

a) 100% b) 300% c) 400% d) 700%

Ans: d

Solution: 100% = + 100/100
= + 1/1, 100%
= + 100/100 = + 1/1
volume = 兀r²h
radius —> 1 : 2
r² —> 1 : 4
height —> 1 : 2
volume —> 1 : 8

+ 7/1 × 100% = 700%

 

 

M Venkat
Director
MVK Publications
Dilsukhnagar
7671002120