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A person's salary increases by 15% and then decreases by 10%. What is the net change in his salary?
A
3.5% increase
B
5% increase
C
3.5% decrease
D
5% decrease
Correct Answer:
A. 3.5% increase
EXPLANATION
Let initial salary = 100. After 15% increase = 115. After 10% decrease = 115 × 0.90 = 103.5. Net change = 3.5% increase
A sum becomes 4 times itself in 15 years at simple interest. What is the rate of interest per annum?
EXPLANATION
If sum becomes 4 times, SI = 3P. SI = P×R×T/100 → 3P = P×R×15/100 → R = 20% p.a.
A shopkeeper marks goods at 60% above cost price. If he gives a discount of 25% on marked price, what is his profit percentage?
EXPLANATION
Let CP = 100. MP = 160. After 25% discount, SP = 160 × 0.75 = 120. Profit% = (120-100)/100 × 100 = 20%
Cost price of an article is Rs. 500. It is sold at 24% profit. What is selling price?
A
Rs. 612
B
Rs. 620
C
Rs. 624
D
Rs. 630
Correct Answer:
C. Rs. 624
EXPLANATION
SP = 500 × 1.24 = Rs. 620. Wait, let me recalculate: 500 + (500 × 0.24) = 500 + 120 = 620. Correct answer should be B.
A boat's speed in still water is 15 km/h. Stream speed is 3 km/h. What is the ratio of downstream to upstream speed?
EXPLANATION
Downstream = 15 + 3 = 18. Upstream = 15 - 3 = 12. Ratio = 18:12 = 3:2
A train travels at 72 km/h. How many metres does it cover in 25 seconds?
A
400 m
B
500 m
C
600 m
D
700 m
EXPLANATION
Speed in m/s = 72 × 5/18 = 20 m/s. Distance = 20 × 25 = 500 m
Pipe A fills a tank in 24 minutes, Pipe B in 36 minutes. If both work together, how long to fill the tank?
A
12.8 minutes
B
14.4 minutes
C
15.6 minutes
D
16.2 minutes
Correct Answer:
B. 14.4 minutes
EXPLANATION
Combined rate = 1/24 + 1/36 = (3+2)/72 = 5/72. Time = 72/5 = 14.4 minutes
A man invests Rs. 8000 at 12% p.a. simple interest for 18 months. What amount does he receive?
A
Rs. 9440
B
Rs. 9600
C
Rs. 9680
D
Rs. 10000
Correct Answer:
A. Rs. 9440
EXPLANATION
SI = (8000 × 12 × 1.5)/100 = 1440. Amount = 8000 + 1440 = Rs. 9440
If 45% of a number equals 180, what is 80% of that number?
EXPLANATION
Number = 180/0.45 = 400. So 80% of 400 = 320
A shopkeeper marks goods 40% above cost price and offers 15% discount. What is his profit percentage?
EXPLANATION
Profit % = [(140 × 85)/100 - 100] = [119 - 100] = 19%
