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A train travels 120 km in 2 hours and then 150 km in 3 hours. What is the average speed of the train?
A
54 km/h
B
55 km/h
C
56 km/h
D
57 km/h
Correct Answer:
A. 54 km/h
Explanation:
Total distance = 120 + 150 = 270 km. Total time = 2 + 3 = 5 hours. Average speed = 270/5 = 54 km/h
If a number is divisible by both 12 and 18, it must be divisible by:
Explanation:
LCM of 12 and 18 = 36. Any number divisible by both 12 and 18 must be divisible by their LCM, which is 36
What is the compound interest on Rs. 10,000 at 10% per annum for 2 years?
A
Rs. 2,000
B
Rs. 2,100
C
Rs. 2,200
D
Rs. 2,300
Correct Answer:
B. Rs. 2,100
Explanation:
CI = P[(1 + r/100)^n - 1] = 10000[(1.1)^2 - 1] = 10000[0.21] = Rs. 2,100
If 5 workers can complete a job in 12 days, how many days will 8 workers take?
A
7 days
B
7.5 days
C
8 days
D
8.5 days
Correct Answer:
B. 7.5 days
Explanation:
Work = 5 × 12 = 60 worker-days. Days for 8 workers = 60/8 = 7.5 days
A shopkeeper buys an item at Rs. 400 and sells it at Rs. 520. What is his profit percentage?
Explanation:
Profit = 520 - 400 = 120. Profit% = (120/400) × 100 = 30%
What is the missing number in the series: 2, 6, 12, 20, ?, 42
Explanation:
Series follows n(n+1): 1×2=2, 2×3=6, 3×4=12, 4×5=20, 5×6=30, 6×7=42
If a:b = 3:4 and b:c = 5:6, then a:b:c is:
A
15:20:24
B
3:4:5
C
15:12:24
D
10:15:18
Correct Answer:
A. 15:20:24
Explanation:
a:b = 3:4, b:c = 5:6. Multiply first by 5 and second by 4: a:b = 15:20, b:c = 20:24. So a:b:c = 15:20:24
In a class of 50 students, 30 study Math and 25 study Science. How many study both?
Explanation:
Using set theory: n(M∪S) = n(M) + n(S) - n(M∩S). 50 = 30 + 25 - n(M∩S). n(M∩S) = 5
What is the value of (2.5)² - (1.5)² / 2?
Explanation:
(2.5)² - (1.5)² / 2 = [6.25 - 2.25] / 2 = 4/2 = 2
If x² + 1/x² = 7, then x + 1/x is:
Explanation:
(x + 1/x)² = x² + 2 + 1/x² = 7 + 2 = 9. So x + 1/x = ±3
