Govt Exams
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Topics in Quantitative Aptitude
A worker can complete a job in 12 days. Another worker can complete it in 18 days. If they work together, how many days will they take?
Correct Answer:
B. 7.2 days
EXPLANATION
Combined rate = 1/12 + 1/18 = 3/36 + 2/36 = 5/36; Time = 36/5 = 7.2 days
Find the LCM of 48, 64, and 96 using prime factorization.
Correct Answer:
C. 384
EXPLANATION
48 = 2⁴×3; 64 = 2⁶; 96 = 2⁵×3; LCM = 2⁶×3 = 64×6 = 384
A shopkeeper buys books at ₹20 each and sells at a profit of 25%. During a sale, he gives a 10% discount. What is his effective profit percentage?
Correct Answer:
A. 12.5%
EXPLANATION
SP = 20 × 1.25 = ₹25; After 10% discount = 25 × 0.9 = ₹22.5; Profit% = (22.5-20)/20 × 100 = 12.5%
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?
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
The HCF of two numbers is 18 and their LCM is 1080. If one number is 108, find the other number.
Correct Answer:
A. 180
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.
Correct Answer:
A. 15,360
EXPLANATION
HCF×LCM = product of numbers. 16×960 = 15,360.
A man walks 5 km/h and covers a distance in 6 hours. If he walks at 6 km/h, how much time saved?
Correct Answer:
B. 1 hour
EXPLANATION
Distance = 5×6 = 30 km. New time = 30/6 = 5 hours. Time saved = 6-5 = 1 hour.
A man's salary increases from ₹40,000 to ₹48,000. What is the percentage increase?
Correct Answer:
C. 20%
EXPLANATION
Increase = 48000 - 40000 = 8000. Percentage = 8000/40000 × 100 = 20%.
A shopkeeper buys goods at ₹80 and marks it up by 25%. After giving 10% discount, what is his profit percentage?
Correct Answer:
B. 12.5%
EXPLANATION
MP = 80×1.25 = ₹100. SP = 100×0.9 = ₹90. Profit = 10/80 × 100 = 12.5%.
A boat covers 24 km upstream in 6 hours and 24 km downstream in 3 hours. Find the speed of the current.
Correct Answer:
A. 2 km/h
EXPLANATION
Upstream speed = 24/6 = 4 km/h. Downstream speed = 24/3 = 8 km/h. Current = (8-4)/2 = 2 km/h.