## Quantitative Aptitude Questions and Answers With Explanation (Practice set 16)

**Q1:****Find the compound interest on Rs. 16,000 at 20% per annum for 9 months, compounded quarterly**

A) 2422 B) 2522

C) 2622 D) 2722

**Q2:****A man sitting in a train which is traveling at 50 kmph observes that a goods train, traveling in the opposite direction, takes 9 seconds to pass him. If the goods train is 280 m long, find its speed.?**

A) 60 B) 62

C) 64 D) 65

**Q3:****Three unbiased coins are tossed. What is the probability of getting at least 2 heads?**

A) 1/4 B) 1/2

C) 3/4 D) 1/3

**Q4:****50 men took a dip in a water tank 40 m long and 20 m broad on a religious day. If the average displacement of water by a man is 4 cu.m, then the rise in the water level in the tank will be:**

A) 20 cm B) 25 cm

C) 35 cm D) 50 cm

**Q5:****An error of 2% in excess is made while measuring the side of a square. The percentage of error in the calculated area of the square is:**

A) 1.04 B) 2.04

C) 3.04 D) 4.04

**Q6:****In a 1 km race, A beats B by 28 meters in 7sec. Find A's time over the course?**

A) 5min,4sec B) 4min,3sec

C) 2min,3sec D) 3min,4sec

**Q7:****The product of two co-prime numbers is 117. Their L.C.M should be**

A) 1 B) 117

C) Equal to their H.C.F D) cannot be calculated

**Q8:**

**A certain sum of money amounts to Rs 1008 in 2 years and to Rs 1164 in 3 ½ years. Find the sum and the rate of interest.**

A) 800, 14% B) 800, 13%

C) 800, 12% D) 800, 19%**Q9:****A certain number of men can finish a piece of work in 100 days. If there were 10 men less, it would take 10 days more for the work to be finished. How many men were there originally?**

A) 75 B) 82

C) 100 D) 110

**Q10:****A, B, C together can do a piece of work in 10 days. All the three started working at it together and after 4 days, A left. Then, B and C together completed the work in 10 more days. In how many days can complete work alone?**

A) 25 B) 24

C) 23 D) 21

** **

**ANSWERS WITH EXPLANATION**

**Answer1: B) 2522****Explanation:**

Principal = Rs. 16000; Time = 9 months =3 quarters;

Rate = 20% per annum = 5% per quarter.

Amount = Rs. [16000 x (1+(5/100))3] = Rs. 18522.

CJ. = Rs. (18522 - 16000) = Rs. 2522

**Answer2: B) 62****Explanation:**

Relative speed =280/9 m / sec = (280/9*18/5) kmph = 112 kmph.

Speed of goods train = (112 - 50) kmph = 62 kmph.

Answer3: B) 1/2

Explanation:

Here S= {TTT, TTH, THT, HTT, THH, HTH, HHT, HHH}.

Let E = event of getting at least two heads = {THH, HTH, HHT, HHH}.

P(E) = n(E) / n(S)

= 4/8= 1/2

**Answer4: B) 25 cm****Explanation:**

Total volume of water displaced =(4 x 50) cu.m = 200 cu.m

Rise in water level = (200/(40×20))=0.25m = 25cm

**Answer5: D) 4.04****Explanation:**

100 cm is read as 102 cm.

A1 = (100*100)Sq.cm

A2 = (102*102)Sq.cm

(A2 - A1) = 102x102−100x100 = (102 + 100) x (102 - 100) = 404 sq.cm.

**Answer6: B) 4min,3sec****Explanation:**

B covers 28 meters in 7sec. So, B's time over the course = (7/28)*100 =250 sec.

Whereas A's time over the course = 250 -7 = 243 sec.

i.e A's time over the course is 4min, 3 sec.

**Answer7: B) 117****Explanation:**

H.C.F of co-prime numbers is 1. So, L.C.M = 117/1 =117

**Answer8: B) 800, 13%****Explanation:**

S.I. for 1 ½ years = Rs (1164 - 1008) = Rs 156 .

S.I. for 2 years = Rs (156 x 2/3 x 2)= Rs 208.

Therefore, Principal = Rs (1008 - 208) = Rs 800.

Now, P = 800, T= 2 and S.I. = 208.

Therefore, Rate = (100 x S.I.) / (P x T) = [ (100 x 208)/(800 x 2)]% = 13%

**Answer9: D) 110****Explanation:**

Originally let there be x men.

Fewer men, More days (Indirect Proportion)

Therefore, (x-10) : x :: 100 :110

=> (x - 10) * 110 = x * 100 => x= 110

**Answer10: A) 25****Explanation:**

(A+B+C) do 1 work in 10 days.

So (A+B+C)'s 1 day work=1/10 and as they work together for 4 days so work is done by them in 4 days=4/10=2/5

Remaining work=1-2/5=3/5

(B+C) take 10 more days to complete 3/5 of work. So( B+C)'s 1 day work=3/50

Now A'S 1 day work=(A+B+C)'s 1 day work - (B+C)'s 1 day work=1/10-3/50=1/25

A does 1/25 work in 1 day

Therefore 1 work in 25 days.

**Also Practice:** *Quantitative Aptitude Questions and Answers With Explanation (Practice set 15)*