Showing 311–320 of 499 questions
Three bells ring at intervals of 8, 12, and 18 minutes. If they ring together at 9:00 AM, when will they ring together again?
A
9:72 AM
B
10:12 AM
C
11:00 AM
D
11:30 AM
Correct Answer:
B. 10:12 AM
Explanation:
LCM(8,12,18) = 72 minutes. 9:00 AM + 72 minutes = 10:12 AM.
HCF of three numbers is 8. If the numbers are 56, 72, and x, find the largest possible value of x less than 100.
Explanation:
HCF(56,72) = 8. x must be multiple of 8 and have HCF with 56,72 as 8. Largest multiple of 8 < 100 is 96.
A trader sells an item at 15% profit. If he had sold it for ₹100 more, his profit would be 25%. Find cost price.
A
₹1000
B
₹1200
C
₹1500
D
₹2000
Explanation:
Let CP = x. SP₁ = 1.15x. SP₂ = 1.25x = 1.15x + 100. 0.1x = 100. x = 1000.
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.
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.
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.
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 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.
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.
Two pipes can fill a tank in 10 hours and 15 hours respectively. A drain empties it in 20 hours. If all three are opened, how long to fill the tank?
A
7.5 hours
B
8.57 hours
C
9 hours
D
10 hours
Correct Answer:
B. 8.57 hours
Explanation:
Net rate = 1/10 + 1/15 - 1/20 = 6/60 + 4/60 - 3/60 = 7/60; Time = 60/7 ≈ 8.57 hours
