21. What is 25% of 25% of 100?
A. 6.25
B. 0.625
C. 62.5
D. 25

सही उत्तर: [A]

हल (Solution):
Correct Answer: A) 6.25
Solution:

(25/100) * (25/100) * 100 = 625 / 100 = 6.25.
22. If the radius of a circle is increased by 50%, its area is increased by:
A. 50%
B. 100%
C. 125%
D. 150%

सही उत्तर: [C]

हल (Solution):
Correct Answer: C) 125%
Solution:

Area depends on the square of radius (r^2).

Net increase = 50 + 50 + (50 * 50 / 100) = 100 + 25 = 125%.
23. If the radius of a circle is increased by 50%, its area is increased by:
A. 50%
B. 100%
C. 125%
D. 150%

सही उत्तर: [C]

हल (Solution):
Correct Answer: C) 125%
Solution:

Area depends on the square of radius (r^2).

Net increase = 50 + 50 + (50 * 50 / 100) = 100 + 25 = 125%.
24. 30% of a number when subtracted from 91 gives the same number. Find the number.
A. 60
B. 70
C. 80
D. 90

सही उत्तर: [B]

हल (Solution):
Correct Answer: B) 70
Solution:

91 - 30% of x = x => 91 = x + 0.3x => 1.3x = 91.

x = 91 / 1.3 = 70.
25. A fruit seller had some apples. He sells 40% apples and still has 420 apples. Originally, he had:
A. 588 apples
B. 600 apples
C. 672 apples
D. 700 apples

सही उत्तर: [D]

हल (Solution):
Correct Answer: D) 700 apples
Solution:

Remaining apples = 100% - 40% = 60%.

60% of Total = 420 => Total = (420 * 100) / 60 = 700.
26. If x is 20% less than y, then find the value of (y - x) / y.
A. 1/5
B. 4/5
C. 5/4
D. 1/4

सही उत्तर: [A]

हल (Solution):
Correct Answer: A) 1/5
Solution:

Let y = 100, then x = 80.

(y - x) / y = (100 - 80) / 100 = 20 / 100 = 1/5.
27. In a school, 70% of students are boys and the number of girls is 504. Find the number of boys.
A. 1176
B. 1008
C. 1200
D. 1500

सही उत्तर: [A]

हल (Solution):
Correct Answer: A) 1176
Solution:

Percentage of girls = 100% - 70% = 30%.

30% = 504 => 1% = 504 / 30 = 16.8.

Number of boys (70%) = 70 * 16.8 = 1176.
28. If 10% of m is the same as 20% of n, then m : n is equal to:
A. 1 : 2
B. 2 : 1
C. 1 : 1
D. 5 : 1

सही उत्तर: [B]

हल (Solution):
Correct Answer: B) 2 : 1
Solution:

(10/100) * m = (20/100) * n => 10m = 20n => m/n = 2/1.

m : n = 2 : 1.
29. If 10% of m is the same as 20% of n, then m : n is equal to:
A. 1 : 2
B. 2 : 1
C. 1 : 1
D. 5 : 1

सही उत्तर: [B]

हल (Solution):
Correct Answer: B) 2 : 1
Solution:

(10/100) * m = (20/100) * n => 10m = 20n => m/n = 2/1.

m : n = 2 : 1.
30. The price of a car depreciates every year by 10%. If its present value is Rs. 3,00,000, what will be its value after 2 years?
A. Rs. 2,40,000
B. Rs. 2,43,000
C. Rs. 2,50,000
D. Rs. 2,70,000

सही उत्तर: [B]

हल (Solution):
Correct Answer: B) Rs. 2,43,000
Solution:

Value after 2 years = 300000 * (90/100) * (90/100) = 300000 * 0.81 = Rs. 2,43,000.