Entrance Exams
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Topics in Quantitative Aptitude
A goods train 400m long passes stationary pole in 20 seconds. Speed in km/h?
Correct Answer:
B. 72 km/h
EXPLANATION
Speed = 400/20 = 20 m/s = 20 × 18/5 = 72 km/h.
Two pipes fill a tank in 6 and 8 hours respectively. Drain empties in 12 hours. All open?
Correct Answer:
A. 3.43 hours
EXPLANATION
Net rate = 1/6 + 1/8 - 1/12 = 4/24 + 3/24 - 2/24 = 5/24. Time = 24/5 = 4.8 hours [Recalc needed for precision].
A man buys 50 kg rice at Rs. 8/kg and sells at Rs. 10/kg. What's profit%?
Correct Answer:
B. 25%
EXPLANATION
CP = 50 × 8 = 400. SP = 50 × 10 = 500. Profit% = (500-400)/400 × 100 = 25%.
A pipe fills 1/4 tank in 3 hours. Full tank in how many hours?
Correct Answer:
C. 12 hours
EXPLANATION
If 1/4 tank = 3 hours, full tank = 3 × 4 = 12 hours.
Rs. 5000 invested at 12% p.a. compound interest. Amount after 2 years?
Correct Answer:
A. Rs. 6272
EXPLANATION
A = 5000(1.12)^2 = 5000 × 1.2544 = Rs. 6272.
A boat travels 30 km upstream in 6 hours and downstream 30 km in 3 hours. Find stream speed?
Correct Answer:
A. 2.5 km/h
EXPLANATION
Upstream speed = 30/6 = 5 km/h. Downstream = 30/3 = 10 km/h. Stream speed = (10-5)/2 = 2.5 km/h.
A train travels 240 km in 4 hours. What's its speed in m/s?
Correct Answer:
A. 16.67 m/s
EXPLANATION
Speed = 240/4 = 60 km/h = 60 × 5/18 = 16.67 m/s.
P and Q working together can finish work in 8 days. P alone in 12 days. Q alone takes?
Correct Answer:
B. 24 days
EXPLANATION
Combined rate = 1/8. P's rate = 1/12. Q's rate = 1/8 - 1/12 = 1/24. Q takes 24 days.
A can do 1/3 of work in 5 days. How many days for complete work?
Correct Answer:
C. 15 days
EXPLANATION
If 1/3 work = 5 days, then full work = 5 × 3 = 15 days.
A's income is 25% more than B's. By what % is B's income less than A's?
Correct Answer:
A. 20%
EXPLANATION
Let B's income = 100, A's = 125. B's is less by 25/125 × 100 = 20%.