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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
View Answer
Answer: option (D)
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
View Answer
Answer: option (C)
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
View Answer
Answer: option (C)
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
View Answer
Answer: option (D)
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
View Answer
Answer: option (C)
Explanation:
Purchase price = Rs. (8748/((1-10/100)^3))=Rs.(8748*10/9*10/9*10/9)= Rs.12000