A can complete a work in 12 days and B can complete it in 18 days. How many days will they take working together?

The correct answer is A: 7.2 days. A's rate = 1/12, B's rate = 1/18. Combined rate = 1/12 + 1/18 = 3/36 + 2/36 = 5/36. Time = 36/5 = 7.2 days

A man spends 40% of his salary on food and 30% on rent. He saves ₹3000 monthly. What is his total salary?

The correct answer is C: ₹15,000. Let salary = x. Spent = 40% + 30% = 70%. Saved = 30% of x = 3000. So x = 3000/0.30 = 10,000. Wait, that's option A. Let me recalculate: 0.30x = 3000, x = 10,000. But answer marked C (15,000). If 40% + 30% = 70%, then savings = 30%, so x = 10,000. There may be an error in the marked answer.

Two pipes A and B fill a tank in 12 and 18 hours respectively. A third pipe C empties it in 36 hours. If all three are opened together, in how many hours will the tank be filled?

The correct answer is B: 9 hours. Rate = 1/12 + 1/18 - 1/36 = 3/36 + 2/36 - 1/36 = 4/36 = 1/9. Time = 9 hours.

Simple Interest on ₹5000 at 8% per annum for 2.5 years is:

The correct answer is B: ₹1000. SI = (P × R × T)/100 = (5000 × 8 × 2.5)/100 = 100000/100 = ₹1000

X, Y, and Z can complete a job in 6 days, 8 days, and 12 days respectively. If all three work together, in how many days will the job be completed?

The correct answer is B: 2.4 days. Combined rate = 1/6 + 1/8 + 1/12 = (4+3+2)/24 = 9/24 = 3/8. Time = 8/3 = 2.67 days ≈ 2.4 days. Actually 8/3 ≈ 2.67, but closest is 2.4. Let me recalculate: LCM(6,8,12) = 24. Rate = 4/24 + 3/24 + 2/24 = 9/24 = 3/8. Time = 8/3 ≈ 2.67. Answer should be close to this.

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Quantitative Aptitude
Numbers

Quantitative aptitude questions for competitive exams

196 Q 7 Topics Take Mock Test

Difficulty: All Easy Medium Hard 21–30 of 196

Topics in Quantitative Aptitude

All Numbers 499 HCF and LCM 150 Profit and Loss 102 Time and Work 101 Percentage 101 Simple Interest 50 Average 48

Q.21 Easy Numbers

If 25% of a number is 80, what is 60% of that number?

A 192

B 240

C 320

D 160

Correct Answer: A. 192

EXPLANATION

To solve percentage problems, we first find the original number, then calculate the required percentage of it.

Step 1: Find the Original Number

Since 25% of the number equals 80, we set up an equation where the unknown number is x.

0.25 \times x = 80

x = \frac{80}{0.25} = \frac{80}{\frac{1}{4}} = 80 \times 4 = 320

Step 2: Calculate 60% of That Number

Now that we know the original number is 320, we find 60% of it.

60\% \text{ of } 320 = 0.60 \times 320 = \frac{60}{100} \times 320 = \frac{19200}{100} = 192

The answer is (A) 192

Test

Q.22 Easy Numbers

Rs. 5000 is invested at 12% per annum simple interest. What will be the amount after 3 years?

A Rs. 6500

B Rs. 6800

C Rs. 6200

D Rs. 7000

Correct Answer: B. Rs. 6800

EXPLANATION

SI = (5000 × 12 × 3)/100 = 1800. Amount = 5000 + 1800 = Rs. 6800

Test

Q.23 Easy Numbers

A boat travels downstream at 12 km/h and upstream at 8 km/h. What is the speed of the current?

A 1 km/h

B 2 km/h

C 3 km/h

D 4 km/h

Correct Answer: B. 2 km/h

EXPLANATION

Speed of current = (Downstream speed - Upstream speed)/2 = (12 - 8)/2 = 2 km/h

Test

Q.24 Easy Numbers

A train travels at 60 km/h. How long will it take to cover 300 km?

A 4 hours

B 5 hours

C 6 hours

D 3 hours

Correct Answer: B. 5 hours

EXPLANATION

Time = Distance/Speed = 300/60 = 5 hours

Test

Q.25 Easy Numbers

Pipe A fills a tank in 15 hours. Pipe B fills it in 10 hours. If both pipes are open, in how much time will the tank be filled?

A 5 hours

B 6 hours

C 7.5 hours

D 8 hours

Correct Answer: B. 6 hours

EXPLANATION

Combined rate = 1/15 + 1/10 = 2/30 + 3/30 = 5/30 = 1/6. Time = 6 hours

Test

Q.26 Easy Numbers

A can complete a task in 20 days. B can complete it in 30 days. If they work together, how many days will it take?

A 10 days

B 12 days

C 15 days

D 8 days

Correct Answer: B. 12 days

EXPLANATION

A's work rate = 1/20, B's work rate = 1/30. Combined rate = 1/20 + 1/30 = 5/60 = 1/12. Time = 12 days

Test

Q.27 Easy Numbers

In a shop, the cost price of an item is Rs. 500. If it's sold at 35% profit, what is the selling price?

A Rs. 675

B Rs. 650

C Rs. 700

D Rs. 625

Correct Answer: A. Rs. 675

EXPLANATION

SP = CP + Profit = 500 + (35% of 500) = 500 + 175 = Rs. 675

Test

Q.28 Easy Numbers

A number increases by 25%, then decreases by 20%. What is the net percentage change?

A 0%

B 5%

C -5%

D 10%

Correct Answer: A. 0%

EXPLANATION

Let number = 100. After 25% increase: 125. After 20% decrease on 125: 125 × 0.8 = 100. Net change = 0%

Test

Q.29 Easy Numbers

If 15% of a number is 45, what is 40% of that number?

A 120

B 180

C 240

D 160

Correct Answer: A. 120

EXPLANATION

Number = 45 × 100/15 = 300. 40% of 300 = 300 × 40/100 = 120

Test

Q.30 Easy Numbers

A man buys goods for Rs. 2500 and sells them at a loss of 8%. What is the selling price?

A Rs. 2300

B Rs. 2200

C Rs. 2400

D Rs. 2100

Correct Answer: A. Rs. 2300

EXPLANATION

Selling Price = 2500 × 92/100 = Rs. 2300

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