M4maths Previous Puzzles

01 Feb 2021 Simple interest

A Certain sum amounted to Rs. 900 at 5% in a time in which Rs. 750 amounted to Rs. 840 at 4%. If the rate of interest is simple, find the sum (approx.)

OPtion

1) 850
2) 500
3) 850.65
4) 780.60
5) 575.50
6) 875.54
7) 900
8) 745
9) 865.50
10) None of the above

Solution

Interest = 840 – 750 = 90
Time = 90 x 100 / 750 x 4 = 3 years
Sum = 100 x amount / 100 x rt
= 100 x 900/( 100 + 5 x 3)
= 780.60 Rs.

Correct Option: 4 Best Solution (3)

29 Jan 2021 Population

Annual increase in population of a city is 4% and the present population is 40000. What will be the population of City after 2 years?

OPtion

1) 43264
2) 42264
3) 43500
4) 44364
5) 44264
6) 43850
7) 43980
8) 42500
9) 43800
10) None of the above

Solution

Population after 2 years = 40000(1+ 4/400)2
= 40000 x 104 x 104/100 x 100
= 43264

Correct Option: 1 Best Solution (6)

28 Jan 2021 Ratio

In the 45 litters mixture of Juice and water, the ratio of Juice and water is 5 : 4. Find the quantity of water required to be added so that resultant mixture will be in ratio 4 : 5.

OPtion

1) 12.50 liters
2) 12.30 liters
3) 11.50 liters
4) 11.0 liters
5) 11.25 liters
6) 10.80 liters
7) 10.25 liters
8) 10.50 liters
9) 11.70 liters
10) None of the above

Solution

Quantity of water required will be = 45(5 x 5 – 4 x 4)/4 (5 + 4)
= 45 x 9/ 4 x 9 = 11.25 liters

Correct Option: 5 Best Solution (0)

27 Jan 2021 Speed

The speed of a van increases by 5kmph after every one hour. If the distance travelled in the first one hour was 55 km, what was the total distance travelled in 8 hours?

OPtion

1) 580km
2) 116km
3) 147km
4) 240km
5) 440km
6) 179km
7) 540km
8) 480km
9) 430km
10) None of the above

Solution

Distance travelled in 1ST hour =55 km
Speed of the van increases by 5 kmph
after every one hour. Hence, distance travelled in 2nd hour =60 km
distance travelled in 3rd hour =65 km
and so on Total distance travelled =(55+60+……..+(8 terms))
=8/2(2*55+(8-1)5) =4(110+35) =580km

Correct Option: 1 Best Solution (2)

26 Jan 2021 CISTERN

A tap can fill a cistern in 11hours, but due to a leakage it took 13hours to fill the cistern. If the cistern is full, in what time will the cistern become empty due to leakage?

OPtion

1) 73.30hrs
2) 77.50hrs
3) 74.50 hrs
4) 78.15 hrs
5) 71.88 hrs
6) 72.77 hrs
7) 71.5 hrs
8) 72.30hrs
9) 80.50 hrs
10) None of these

Solution

1/11-1/13 = 13-11/143
=>2/143 =>1/71.5
=>71.5hours

Correct Option: 7 Best Solution (3)

25 Jan 2021 AGE

The present ages of Vijay and Shubham differ by 35 years. 3 years later, Shubham would be 4.5 times as old as Vijay. What is the present age of Shubham?

OPtion

1) 37 years
2) 38 Years
3) 39 years
4) 45 years
5) 44 years
6) 41 years
7) 40 years
8) 42 years
9) 48 years
10) None of these

Solution

Let the present age of Shubham be x and Vijay be y
So x-y = 35 ----(i)
3 year later
(x+3) =4.5(y+3)
=> x = 4.5y + 10.5
Putting x value in (i)
4.5y + 10.5 - y = 35
=>3.5y = 24.5
=> y = 7 and x = 35+7 = 42

Correct Option: 8 Best Solution (3)

22 Jan 2021 STREAMS

Ajinkya can row upstream at 20 kmph and downstream at approx. 18.65 mph. The speed of the stream is?

OPtion

1) 5
2) 8
3) 2.5
4) 4.5
5) 3
6) 4
7) 3.5
8) 7
9) 6
10) None of the above

Solution

Speed in upstream = 20 kmph
Speed in downstream = 18.65 mph = 30 kmph
So the speed of stream = ½ (30 – 20) = 5 kmph

Correct Option: 1 Best Solution (3)

21 Jan 2021 Age

A father said to his son that he was thrice of his age 15 years before and will be twice of his age 10 years hence. Difference of the ages of father and son is

OPtion

1) 24
2) 50
3) 32
4) 35
5) 40
6) 12
7) 22
8) 34
9) 28
10) 38

Solution

Let the age of father is f and that of son is s at present
According to the given conditions
f - 15 = 3 (s-15)
=> f - 3s = -30 (i)
f + 10 = 2 (s+10)
=> f - 2s = 10 (ii)
On solving (i) and (ii), we get f = 90; s = 40

Correct Option: 2 Best Solution (0)

20 Jan 2021 Work

A forms a wall in 10 days and B forms it in 15 days. A and B start the work of forming wall together
but after 2 days A leaves the work. How many days are required for making the remaining wall by B?

OPtion

1) 6
2) 9
3) 8
4) 10
5) 12
6) 15
7) 16
8) 20
9) 5
10) None of the above

Solution

One day work of A = 1/10
One day work of B = 1/15
One day work of A and B = 1/10 + 1/15= 1/6
After 2 days of work remaining work = 1- (2*1/6) = 4/6
No. of days required by B for doing this work = (4/6) / (1/15 = 10

Correct Option: 4 Best Solution (2)

19 Jan 2021 Investment

Kapil Pandey invests in a 20% stock at 180. The interest obtain by him is?

OPtion

1) 8%
2) 8.5%
3) 12.5%
4) 12%
5) 10.5%
6) 11.5%
7) 11.11%
8) 13%
9) 13.5%
10) None of the above

Solution

By investing Rs. 180, income derived = Rs. 20
By investing Rs. 100, income derived = Rs. (20/180 x 100) = Rs. 11.11
Interest Obtain = 11.11%

Correct Option: 7 Best Solution (2)