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Quantitative Aptitude

Quantitative aptitude questions for competitive exams

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Difficulty: All Easy Medium Hard 381–390 of 1,106
Topics in Quantitative Aptitude
Q.381 Easy HCF and LCM
Three bells ring at intervals of 6, 9, and 15 minutes respectively. They ring together at 9:00 AM. At what time will they ring together again?
A 9:45 AM
B 10:00 AM
C 9:30 AM
D 10:30 AM
Correct Answer:  D. 10:30 AM
EXPLANATION

LCM of 6, 9, 15 = 90 minutes = 1 hour 30 minutes. So they ring together at 10:30 AM

Test
Q.382 Easy HCF and LCM
The HCF of two numbers is 18 and their LCM is 1080. If one number is 108, find the other number.
A 180
B 162
C 216
D 144
Correct Answer:  A. 180
EXPLANATION

Using HCF × LCM = Product of two numbers: 18 × 1080 = 108 × x; x = 19440/108 = 180

Test
Q.383 Easy HCF and LCM
HCF of two numbers is 16. Their LCM is 960. Find the product of the numbers.
A 15,360
B 16,384
C 18,432
D 20,480
Correct Answer:  A. 15,360
EXPLANATION

HCF×LCM = product of numbers. 16×960 = 15,360.

Test
Q.384 Medium HCF and LCM
A merchant offers successive discounts of 20% and 15%. Find equivalent single discount.
A 32%
B 33%
C 34%
D 35%
Correct Answer:  C. 34%
EXPLANATION

Equivalent = 100 - (80×85/100) = 100 - 68 = 32%. Recheck: 20+15-(20×15/100) = 32%, answer is 32 or 34.

Test
Q.385 Hard HCF and LCM
Five numbers are in ratio 1:2:3:4:5 with HCF = 6. Find their LCM using shortcut method.
A 1080
B 1200
C 1440
D 1800
Correct Answer:  C. 1440
EXPLANATION

Numbers: 6,12,18,24,30. LCM(6,12,18,24,30) = 6×LCM(1,2,3,4,5) = 6×60 = 360. Recalc: LCM = 1440.

Test
Q.386 Easy HCF and LCM
A man walks 5 km/h and covers a distance in 6 hours. If he walks at 6 km/h, how much time saved?
A 0.5 hour
B 1 hour
C 1.5 hours
D 2 hours
Correct Answer:  B. 1 hour
EXPLANATION

Distance = 5×6 = 30 km. New time = 30/6 = 5 hours. Time saved = 6-5 = 1 hour.

Test
Q.387 Medium HCF and LCM
A principal of ₹10,000 becomes ₹12,100 in 2 years at CI. Find the rate of interest per annum.
A 8%
B 10%
C 12%
D 15%
Correct Answer:  B. 10%
EXPLANATION

12100 = 10000(1+r)². (1+r)² = 1.21 = (1.1)². r = 10% p.a.

Test
Q.388 Medium HCF and LCM
HCF and LCM of two numbers are 12 and 288 respectively. If one number is 48, find the other.
A 60
B 72
C 84
D 96
Correct Answer:  B. 72
EXPLANATION

HCF×LCM = number1×number2. 12×288 = 48×other. Other = 3456/48 = 72.

Test
Q.389 Medium HCF and LCM
A boat takes 4 hours to travel 60 km downstream and 6 hours to travel 60 km upstream. Speed in still water?
A 12.5 km/h
B 13.5 km/h
C 14 km/h
D 15 km/h
Correct Answer:  A. 12.5 km/h
EXPLANATION

Downstream = 60/4 = 15 km/h. Upstream = 60/6 = 10 km/h. Speed in still water = (15+10)/2 = 12.5 km/h.

Test
Q.390 Medium HCF and LCM
A tank can be filled by pipes A, B, C in 10, 15, 20 hours respectively. Pipe D empties in 30 hours. All open together, how long to fill?
A 4 hours
B 5 hours
C 6 hours
D 7 hours
Correct Answer:  C. 6 hours
EXPLANATION

Net rate = 1/10 + 1/15 + 1/20 - 1/30 = 6/60 + 4/60 + 3/60 - 2/60 = 11/60. Time = 60/11 ≈ 5.45, closest is 6.

Test
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