M4maths Previous Puzzles

26 Apr 2017 Root and Power

7^x * 3^2 = 504
Find 7^(x+2) =?

OPtion

1) 2144
2) 2800
3) 2695
4) 2714
5) 2344
6) 2844
7) 2944
8) 2774
9) 2644
10) None of these

Solution

7^x * 3^2 = 504
7^x = 504/9 = 56

7^(x+2) = (7^x) * (7^2) = 56*7^2 = 56*49 = 2744

Correct Option: 10 Best Solution (11)

25 Apr 2017 Simple Interest

Raima took a loan of Rs. 1500 with simple interest for as many years as the rate of interest. If she paid Rs. 960 as interest at the end of the loan period, what was the rate of interest?

OPtion

1) 6 %
2) 6.5 %
3) 6.25%
4) 9.00 %
5) 8.00 %
6) 7.25 %
7) 7.50 %
8) 8.50 %
9) 8.75 %
10) None of these

Solution

SI = PRT/100
Let Rate of Interest be R => Also loan period be R Years
960 = 1500*R*R/100
R^2 = 960/15 = 64
=> R = 8.00 %

Correct Option: 5 Best Solution (8)

24 Apr 2017 Series

What is the sum of 8th and 9th term of following series
2, 3, 5, 7, 11, 13, 17, .....

OPtion

1) 19
2) 20
3) 21
4) 42
5) 41
6) 40
7) 37
8) 38
9) 39
10) None of these

Solution

Series is prime number: 2, 3, 5, 7, 11, 13, 17, 19, 23....
8th+9th term = 19+23 = 42

Correct Option: 4 Best Solution (17)

21 Apr 2017 Find the value

If 3^(x - y) = 81 and 3^(x + y) = 729
Find value of x*y

OPtion

1) 1
2) 2
3) 3
4) 4
5) 5
6) 6
7) 7
8) 8
9) 9
10) 10

Solution

3^(x - y) = 3^4
x-y = 4 ---(i)

3^(x + y) = 3^6
x+y = 6 ---(i)

Adding (i) and (ii) and solving we get
x = 5
y = 1

So x*y = 5*1 = 5

Correct Option: 5 Best Solution (0)

20 Apr 2017 Trains

Two bullet trains, one from Jammu to Delhi and the other from Delhi to Jammu, start simultaneously. After they meet, the trains reach their destinations after 4 hours and 8 hours respectively. The ratio of their speeds is:

OPtion

1) 1:2
2) 1:4
3) 2:3
4) 2:5
5) 3:4
6) 3:5
7) 2:1
8) 3:2
9) 5:2
10) None of these

Solution

Let us name the trains as A and B. Given
Time taken by Train A to reach destination after meeting Train B = a = 4 Hours
Time taken by Train B to reach destination after meeting Train A = b = 8 Hours

(A's speed) : (B's speed) = sq. root(b) : sq. root(a)
=> 8^(1/2) : 4^(1/2)
=> 2*2^(1/2) : 2
=> 2^(1/2) : 1

Option 10)

Correct Option: 10 Best Solution (1)

19 Apr 2017 Stocks and Share

The market value of a 12.5% stock, in which an income of Rs. 720 is derived by investing Rs. 9000, brokerage being 1/2 %, is:

OPtion

1) 156.75
2) 156.25
3) 155.75
4) 155.25
5) 155.50
6) 155.00
7) 156.50
8) 156.00
9) 157.25
10) None of these

Solution

For an income of Rs. 720, investment = Rs. 9000.

For an income of Rs. 12.5, investment = Rs. (9000/720) * 12.5 = 156.25
For a Rs. 100 stock, investment = Rs. 156.25

Market value of Rs. 100 stock = Rs. 156.25 - 0.5 = Rs. 155.75

Correct Option: 3 Best Solution (9)

18 Apr 2017 Age

At present, the ratio between the ages of Arun and Deepak is 3 : 2. After 13 years, Arun's age will be 34 years. What would be the age of Deepak after 8 years from now ?

OPtion

1) 14 Years
2) 15 Years
3) 17 Years
4) 18 Years
5) 19 Years
6) 20 Years
7) 21 Years
8) 22 Years
9) 23 Years
10) None of these

Solution

Let the present ages of Arun and Deepak be 3x years and 2x years respectively. Then,

3x + 13 = 34 => 3x = 21
x = 7
Deepak's present age = 2x = 14 years.
Deepak's Age after 8 years = 14 + 8 = 22 Years

Correct Option: 8 Best Solution (11)

17 Apr 2017 Simple Interest

How much time will it take for an amount of Rs. 300 to yield Rs. 123 as interest at 4.1% per annum of simple interest?

OPtion

1) 4 Years
2) 4.5 Years
3) 5 Years
4) 5.5 Years
5) 6 Years
6) 7 Years
7) 8 Years
8) 9 Years
9) 10 Years
10) None of these

Solution

SI = PRT/100

123 = 300*4.1*T/100
=> T = 10 Years

Correct Option: 9 Best Solution (15)

14 Apr 2017 Ratio

If a/b = 7/3, b/c = 1/2, c/d = 6/7, e/f = 8/9 and d/e = 7/10 then what is the value of abc/def ?

OPtion

1) 1
2) 4/25
3) 2/25
4) 3/4
5) 4/5
6) 6/25
7) 8/5
8) 8/25
9) 8/30
10) None of these

Solution

a/d = (a/b)*(b/c)*(c/d) = (7/3)*(1/2)*(6/7) = 1
b/e = (b/c)*(c/d)*(d/e) = (1/2)*(6/7)*(7/10) = 3/10
c/f = (c/d)*(d/e)*(e/f) = (6/7)*(7/10)*(8/9) = 8/15

So abc/def = (a/d)*(b/e)*(c/f) = (1)*(3/10)*(8/15) = 4/25

Option 2)

Correct Option: 2 Best Solution (10)

13 Apr 2017 Runs Scored

In a cricket match, Team A scored 240 runs without losing a wicket. The score consisted of byes,
wides and runs scored by two opening batsmen: Ram and Shyam. The runs scored by the two batsmen are 11 times wides. There are 7 more wides than byes. If the ratio of the runs scored by Ram and Shyam is 5:6, then the percentage of run scored by Ram out of total score of Team A is:

OPtion

1) 39.6
2) 35.42
3) 41.2
4) 41.8
5) 42.5
6) 43.4
7) 44.6
8) 45.5
9) 46.0
10) None of these

Solution

Answer: 39.6
Let Runs Scored by Ram+Shyam be x, byes be y and wides be z
As per question
x = 11z and z = 7+y

So Total runs = x+y+z = 11z+z-7+z = 240
13z-7 = 240
= > z= 19
Therefore x = 11*19 = 209
Runs scored by Ram = 209*5/11 = 95

Percent of total run scored by Ram = (95/240)*100 = 39.6%
Option 1)

Correct Option: 1 Best Solution (5)