Showing 81–90 of 151 questions
in HCF and LCM
The HCF of two numbers is 18 and their LCM is 1080. If one number is 108, find the other number.
Explanation:
Using HCF × LCM = Product of two numbers: 18 × 1080 = 108 × x; x = 19440/108 = 180
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.
A merchant offers successive discounts of 20% and 15%. Find equivalent single discount.
Explanation:
Equivalent = 100 - (80×85/100) = 100 - 68 = 32%. Recheck: 20+15-(20×15/100) = 32%, answer is 32 or 34.
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
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.
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.
A principal of ₹10,000 becomes ₹12,100 in 2 years at CI. Find the rate of interest per annum.
Explanation:
12100 = 10000(1+r)². (1+r)² = 1.21 = (1.1)². r = 10% p.a.
HCF and LCM of two numbers are 12 and 288 respectively. If one number is 48, find the other.
Explanation:
HCF×LCM = number1×number2. 12×288 = 48×other. Other = 3456/48 = 72.
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.
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.
Two trains of length 100m each run towards each other at 50 km/h and 70 km/h. Time to cross each other completely?
A
3 seconds
B
4 seconds
C
5 seconds
D
6 seconds
Correct Answer:
D. 6 seconds
Explanation:
Relative speed = 50+70 = 120 km/h = 100/3 m/s. Distance = 100+100 = 200m. Time = 200÷(100/3) = 6 seconds.
