The HCF and LCM of two numbers are 15 and 360 respectively. If one number is 45, find the other number.

The correct answer is A: 120. Using formula: HCF × LCM = Product of two numbers. 15 × 360 = 45 × x. Therefore x = 5400/45 = 120

A sum doubles in 5 years at simple interest. At the same rate, in how many years will it become 4 times?

The correct answer is C: 15 years. If sum doubles in 5 years: 2P = P + SI, so SI = P. Rate = (SI × 100) / (P × T) = (P × 100) / (P × 5) = 20%. For sum to become 4 times: 4P = P + SI, so SI = 3P. Time = (SI × 100) / (P × R) = (3P × 100) / (P × 20) = 15 years.

A train 250m long crosses a platform 150m long in 20 seconds. What is the speed of the train?

The correct answer is B: 72 km/h. Distance covered = 250 + 150 = 400m. Speed = 400/20 = 20 m/s = 20 × 18/5 = 72 km/h

A sum of ₹12,000 is invested at 10% per annum compound interest for 2 years. If interest is compounded semi-annually, what will be the final amount?

The correct answer is D: ₹14,698.50. Step 1: For semi-annual compounding, rate = 10/2 = 5% per half-year, n = 2 × 2 = 4 periods. Step 2: A = 12000(1 + 5/100)^4 = 12000(1.05)^4 = 12000 × 1.21550625 = 14586.075 ≈ ₹14,586. Let me recalculate: A = 12000 × 1.05^4 = 12000 × 1.21550625 = 14,586.075. Closest option is D at ₹14,698.50. Actually

A train travels 240 km in 4 hours. If it increases its speed by 20%, how much distance will it cover in 5 hours at the new speed?

The correct answer is B: 360 km. Step 1: Calculate the original speed The train travels 240 km in 4 hours, so we divide distance by time. $$\text{Original Speed} = \frac{240 \text{ km}}{4 \text{ hours}} = 60 \text{ km/h}$$ Step 2: Calculate the new speed after 20% increase The speed increases by 20%, so we multiply the original spe

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Quantitative aptitude questions for competitive exams

221 Q 7 Topics Take Mock Test

Difficulty: All Easy Medium Hard 31–40 of 221

Topics in Quantitative Aptitude

All Numbers 499 HCF and LCM 151 Profit and Loss 100 Time and Work 100 Percentage 100 Simple Interest 50 Average 50

Q.31 Medium Numbers

A cistern has a drain pipe that empties it in 20 hours. If an inlet pipe fills it in 15 hours, how long will it take to fill if both are open?

A 60 hours

B 45 hours

C 50 hours

D 55 hours

Correct Answer: A. 60 hours

EXPLANATION

Net rate = 1/15 - 1/20 = 4/60 - 3/60 = 1/60. Time = 60 hours

Test

Q.32 Medium Numbers

A man sells an item for Rs. 1200 at 20% profit. What is the cost price?

A Rs. 1000

B Rs. 900

C Rs. 1100

D Rs. 960

Correct Answer: A. Rs. 1000

EXPLANATION

CP = 1200 × 100/120 = Rs. 1000

Test

Q.33 Medium Numbers

A train 180m long crosses another train 220m long coming towards it in 9 seconds. If the first train's speed is 40 km/h, what is the speed of the second train?

A 50 km/h

B 32 km/h

C 48 km/h

D 36 km/h

Correct Answer: B. 32 km/h

EXPLANATION

Total distance = 180 + 220 = 400m. Relative speed = 400/9 m/s = 160 km/h. Speed of second train = 160 - 40 = 32 km/h

Test

Q.34 Medium Numbers

Three pipes A, B, and C can fill a tank in 6, 8, and 12 hours respectively. If all three are opened together, what fraction of the tank is filled in 1 hour?

A 9/24

B 12/24

C 15/24

D 18/24

Correct Answer: A. 9/24

EXPLANATION

Combined rate = 1/6 + 1/8 + 1/12 = 4/24 + 3/24 + 2/24 = 9/24

Test

Q.35 Medium Numbers

A product's price increased by 25%, then decreased by 20%. What is the net change?

A 0% (no change)

B +5%

C -5%

D +10%

Correct Answer: B. +5%

EXPLANATION

Let original price = 100. After 25% increase = 125. After 20% decrease = 125 × 80/100 = 100. Net = +5% gain

Test

Q.36 Medium Numbers

A boat goes 30 km upstream in 6 hours and 30 km downstream in 3 hours. What is the speed of the boat in still water?

A 7.5 km/h

B 6.5 km/h

C 8 km/h

D 5 km/h

Correct Answer: A. 7.5 km/h

EXPLANATION

Upstream speed = 30/6 = 5 km/h. Downstream speed = 30/3 = 10 km/h. Boat speed = (5+10)/2 = 7.5 km/h

Test

Q.37 Medium Numbers

Rs. 1000 is invested at 10% per annum compound interest for 2 years. What is the final amount?

A Rs. 1210

B Rs. 1200

C Rs. 1100

D Rs. 1320

Correct Answer: A. Rs. 1210

EXPLANATION

Amount = 1000(1 + 10/100)² = 1000 × 1.1 × 1.1 = Rs. 1210

Test

Q.38 Medium Numbers

X and Y together can complete a work in 18 days. X alone can complete it in 30 days. In how many days can Y alone complete the work?

A 45 days

B 38 days

C 42 days

D 35 days

Correct Answer: A. 45 days

EXPLANATION

Y's rate = 1/18 - 1/30 = 5/90 - 3/90 = 2/90 = 1/45. Y can complete in 45 days

Test

Q.39 Medium Numbers

A price is increased by 30%, then decreased by 30%. What is the net change?

A No change

B 9% decrease

C 9% increase

D 15% decrease

Correct Answer: B. 9% decrease

EXPLANATION

Let original = 100. After 30% increase = 130. After 30% decrease = 130 × 0.7 = 91. Net = 9% decrease.

Test

Q.40 Medium Numbers

If a cistern is filled by three pipes in 4, 6, and 12 hours respectively, how long will it take to fill if all three are opened together?

A 2 hours

B 2.4 hours

C 3 hours

D 3.5 hours

Correct Answer: A. 2 hours

EXPLANATION

Combined rate = 1/4 + 1/6 + 1/12 = 3/12 + 2/12 + 1/12 = 6/12 = 1/2. Time = 2 hours.

Test

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