Top 25 - Part 2

1. Algebra

If:

2x + 7 = 21

find x.

A) 5 B) 6 C) 7 D) 8

Answer: B) 7

Actually:

2x + 7 = 21
2x = 14
x = 7

Therefore the correct answer is:

C) 7

2. Mensuration

Find the area of a rectangle whose length is 15 cm and breadth is 8 cm.

A) 100 cm² B) 110 cm² C) 120 cm² D) 130 cm²

Answer: C) 120 cm²

Area = Length × Breadth
     = 15 × 8
     = 120 cm²

3. Percentage

A salary of ₹30,000 is increased by 15%. What is the new salary?

A) ₹33,500 B) ₹34,000 C) ₹34,500 D) ₹35,000

Answer: C) ₹34,500

15% of 30000 = 4500

New salary = 30000 + 4500
           = ₹34,500

4. Profit and Loss

An article is bought for ₹1,200 and sold for ₹1,080. Find the loss percentage.

A) 5% B) 8% C) 10% D) 12%

Answer: C) 10%

Loss = 1200 - 1080
     = 120

Loss % = 120/1200 × 100
       = 10%

5. Ratio

Divide ₹900 in the ratio 2:3:4.

A) ₹100, ₹300, ₹500 B) ₹200, ₹300, ₹400 C) ₹180, ₹300, ₹420 D) ₹150, ₹300, ₹450

Answer: B) ₹200, ₹300, ₹400

Total parts = 2 + 3 + 4 = 9

One part = 900/9 = 100

2 parts = 200
3 parts = 300
4 parts = 400

6. Average

The average age of 4 students is 20. A fifth student joins and the average becomes 22. Find the fifth student’s age.

A) 28 B) 30 C) 32 D) 34

Answer: C) 30

Explanation:

Original total:

4 × 20 = 80

New total:

5 × 22 = 110

New student’s age:

110 - 80 = 30

Therefore the correct option is B) 30, not C.

Answer: B) 30 years

7. Time and Work

A can finish a job in 10 days and B in 15 days. How long will they take together?

A) 5 days B) 6 days C) 7 days D) 8 days

Answer: B) 6 days

1/10 + 1/15
= 3/30 + 2/30
= 5/30
= 1/6

8. Speed

A man walks at 5 km/h. How far will he travel in 2 hours 24 minutes?

A) 10 km B) 11 km C) 12 km D) 14 km

Answer: C) 12 km

2 hours 24 minutes
= 2.4 hours

Therefore:

Distance = 5 × 2.4
         = 12 km

9. Relative Speed

Two cars travel in opposite directions at 50 km/h and 70 km/h. What is their relative speed?

A) 20 km/h B) 50 km/h C) 70 km/h D) 120 km/h

Answer: D) 120 km/h

Relative speed = 50 + 70
               = 120 km/h

10. Simple Interest

Find the amount on ₹8,000 at 5% simple interest for 2 years.

A) ₹8,400 B) ₹8,800 C) ₹9,000 D) ₹9,200

Answer: B) ₹8,800

SI = 8000 × 5 × 2 / 100
   = 800

Amount = 8000 + 800
       = ₹8,800

11. Compound Interest

Find the compound interest on ₹5,000 at 10% per annum for 2 years.

A) ₹1,000 B) ₹1,050 C) ₹1,100 D) ₹1,200

Answer: B) ₹1,050

Amount = 5000 × 1.1²
       = 6050

CI = 6050 - 5000
   = ₹1,050

12. Mixture

A 20-litre mixture contains milk and water in the ratio 3:1. How much water is present?

A) 4 L B) 5 L C) 6 L D) 8 L

Answer: B) 5 L

Total parts = 4

Water = 1/4 × 20
      = 5 L