M4maths Previous Puzzles

06 Mar 2019 Age

At the time of marriage, a man was 5 years elder to his wife. 16 years after their marriage, his age is 8/7 times the age of his wife. What was wife's age at the time of marriage ?

OPtion

1) 16
2) 27
3) 17
4) 19
5) 20
6) 21
7) 22
8) 23
9) 24
10) None of these

Solution

let wifes age= x
husband age = x+5
now after 16 years of marriage
Wife's age = x+16
Husband's age = x+16+5 = x+21


8/7(x+16)=x+21
=> 8x+16*8 = 7x+21*7
Solving we get = 19

Correct Option: 4 Best Solution (0)

05 Mar 2019 GP

If the second term of a G.P. is 9 and sum of the infinite terms is 40.5, then what will be the 3rd term?
Given that the first term is greater than 14.

OPtion

1) 4.5
2) 6
3) 7.5
4) 1.5
5) 1.0
6) 3.0
7) 3.5
8) 2.5
9) 0.333
10) None of these

Solution

nth term = a * r ^ (n-1)
=> For 2nd term => 9 = a*r^(2-1)
=> 9 = ar
=> r = 9/a

Sum of infinite terms in G.P = a/(1-r)

Sum of infinite terms in G.P => 40.5 = a/(1-r)
=> 40.5 - 40.5r = a
=> 40.5 = a + 40.5*9/a
=> 81a = 2a^2 + 729

Solving we get a = 27 or 13.5
As the first term is greater than 15, hence 13.5 is ruled out

So r = 9/27 = 1/3

Hence 3rd term => 27*(1/3)^(3-1) = 27*(1/3)^2 = 27/9 = 3

Correct Option: 6 Best Solution (7)

04 Mar 2019 Percentage

A person spends 20% of his salary on food, 35% on house rent, 20% on conveyance and 10% of the remaining on entertainment. If his savings at the end of the month is Rs. 23700, then his salary per month in rupees is:

OPtion

1) 158600
2) 158100
3) 158200
4) 158300
5) 158000
6) 158500
7) 158680
8) 158700
9) 158800
10) None of these

Solution

Food 20%
Rent 35%
Coveyance 20%
Entertainment 10%
Saving% 100 - (20+35+20+10) = 15%

Saving Amount 23700

15% of salary = 23700
100% of salary = 23700*100/15

So Salary 158000

Correct Option: 5 Best Solution (0)

01 Mar 2019 Even Number

How many factors of 997972488 are even numbers?

OPtion

1) 125
2) 75
3) 120
4) 135
5) 60
6) 75
7) 180
8) 150
9) 90
10) None of these

Solution

997972488 = 73^2 * 17^2 * 3^4 * 2^3

Any factor of this number should be of the form 73^a * 17^b * 3^c * 2^d

For the factors of this number to be an even number d should be non 0

a can take values 0, 1, 2
b can take values 0, 1, 2
c can take values 0, 1, 2, 3, 4
d can take values 1, 2, 3


Total number of odd factors = 3*3*5*3= 135



Option 4)

Correct Option: 4 Best Solution (1)

28 Feb 2019 Rank

Pappu ranked twenty-fifth from the top and nineth from the bottom among the students who passed the annual examination in a class. If the number of students who failed in the examination was 13 . How many students appeared for the examination?

OPtion

1) 33
2) 42
3) 44
4) 45
5) 46
6) 43
7) 47
8) 48
9) 34
10) None of these

Solution

Total number of students who passed = 25+9-1 = 33
Number of students who failed in exam = 13
total=33+13=46

Correct Option: 5 Best Solution (0)

27 Feb 2019 Profit & Loss

If on an item a company gives 35% discount, they earn 20% profit. If they now give 20% discount then what is the profit percentage.

OPtion

1) 50.000
2) 48.000
3) 47.000
4) 46.000
5) 45.000
6) 47.696
7) 46.696
8) 47.069
9) 45.696
10) None of these

Solution

Let the CP of item would be 100
After 35% disucount company still makes 20% profit so discounted price is = 120

Lets assume SP without discount is X, so after 35% discount discounted SP = 0.65X
So 0.65 X = 120, X= 184.62

So SP without discount or MRP = 184.62
New Discount Percent = 20%

Actual SP when discount is 20% = 0.8 * 184.62 = 147.696

Profit when CP is 100 = 147.696 - 100 = 47.696

Profit % = 47.696%

Correct Option: 6 Best Solution (3)

26 Feb 2019 Series

24, 32, ?, 62, 74, 102

OPtion

1) 36
2) 42
3) 44
4) 46
5) 48
6) 50
7) 38
8) 52
9) 54
10) None of these

Solution

24 + (2*4) = 32
32 + (3*2) = 38
38 + (3*8) = 62
62 + (6*2) = 74
74 + (7*4) = 102

Correct Option: 7 Best Solution (0)

25 Feb 2019 Ratio

A man distributes 0.395 of his money to his wife and 0.450 to his son. He has still Rs.3,875 left with him. How much did his wife get?

OPtion

1) 25000
2) 22500
3) 20000
4) 18000
5) 16000
6) 09875
7) 17500
8) 15000
9) 14000
10) None of these

Solution

Part left with man = 1 - (0.395+0.450) = 0.155

0.155 is left with him which amounts to 3,875
So 0.395 which is wife's share = 3875*(0.395/0.155) = Rs. 9875

Correct Option: 6 Best Solution (0)

22 Feb 2019 Interest

Mohita deposits Rs.15,000 in her bank account for 6 years to earn a simple interest of 11.5 %.what amount will she get after 6 years?

OPtion

1) 10550
2) 10950
3) 10350
4) 10450
5) 10650
6) 25350
7) 25450
8) 25550
9) 25650
10) None of these

Solution

SI = PRT/100 = 15000*11.5*6/100 = 10350

A= P+SI = 15000 + 10350 = 25350

Correct Option: 6 Best Solution (3)

21 Feb 2019 Combination

There are 31 students in a class, number of girls is one more than number of guys. we need to form a team of four students. all four in the team cannot be from same gender and number of girls and guys in the team should NOT be equal. How many ways can such a team be made?

OPtion

1) 15680
2) 15480
3) 15280
4) 15180
5) 15380
6) 15080
7) 15600
8) 15580
9) 15880
10) None of these

Solution

boys=15 and girls=16 now the combinations are {girl,girl,girl,boy} or {boy,boy,boy,girl}
so 16c3*15c1 + 15c3*16c1 = 560*15 + 455*16 = 15680

Correct Option: 1 Best Solution (6)