# Percentages ( 21 to 25 )

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Percentages ( 21 to 25 ):

# APTITUDE QUESTIONS (PERCENTAGES):

21. Rohit spends 40% of his salary on food, 20% on house rent, 10% on entertainment and 10% on conveyance. If his savings at the end of a month are Rs.2500, then his monthly salary is:

A)    Rs.6000

B)    Rs.7500

C)    Rs.8000

D)    Rs.12500

E)    None of these

Explanation:

Saving = [100 – (40 + 20 + 10 + 10)] % = 20%. Let the monthly salary be Rs. x
Then, 20% of x = 2500  (20/100) x=2500  x = 2500 * 5 = 12500

22. The sum of the number of boys and girls in a school is 150. If the number of boys is y, then the number of girls becomes y% of the total number of students. The number of boys is:

A)    40

B)    50

C)    60

D)    90

E)    None of these

Explanation:

We have: y + y% of 150 = 150

y + y/100*150=150 

(5/2) y=150 

y = (150* 2)/5=60

23. In a city, 40% of the people are illiterate and 60% are poor. Among the rich, 10% are illiterate. What percentage of the poor population is illiterate?

A)    36%

B)    40%

C)    60%

D)    50%

E)    None of these

Explanation:

Let the total population be x. Then,
Poor population = (60/100) x= (3/5) x. Illiterate population = (40/100) x = (2/5) x
Illiterate rich = 10% of (100 – 60) % of x = (10/100*40/100*x)= x/25
Illiterate poor = ((2/5)x-x/25) = 9x/25
∴ Required percentage = (9x/25*5/3x*100)%= 60%

24. A building worth Rs. 1,72,800 is constructed on land worth Rs. 51,200. After how many years will the value of both be the same if land appreciates at 20% p.a. and building depreciates at 20% p.a.?

A)    1(1/2)

B)    2

C)    2(1/2)

D)    3

E)    None of these

Explanation:

Let the required time be n years. Then, 51200 * (1+20/100)^n = 172800 * (1-20/100)^n
 (12/10)^n * (10/8)^n = 172800/51200  (12/8)^n = 1728/512 = (12/8)^3  n = 3

25. The value of a machine depreciates at the rate of 10% every year. It was purchased 3 years ago. If its present value is Rs. 8748 its purchase price was:

A)    Rs. 10,000

B)    Rs. 11, 372

C)    Rs. 12,000

D)    Rs. 12, 500

E)    None of these