M4maths Previous Puzzles

09 May 2018 Probability

A prime number less than 60 is randomly picked, what is probability that one of its digit will be 3?

OPtion

1) 1/2
2) 6/15
3) 7/17
4) 5/17
5) 1/8
6) 9/16
7) 7/16
8) 2/7
9) 8/17
10) None of these

Solution

Total number of prime numbers less than 60 = 17 => 2, 3, 5, 7, 11, 13, 17, 19, 23, 29, 31, 37, 41, 43, 47, 53, 59
Number of positive outcomes i.e. number where at least one of its digit is 3 = 7

Probability = 7/17

Correct Option: 3 Best Solution (0)

08 May 2018 Percentage

If Rs.12525 is to be divided among Amar, Akbar and Anthony so that Amar receives 15% more than Akbar and Akbar receives 30% less than Anthony, then eighty percent of Amar's shares is

OPtion

1) Rs.4045
2) Rs.4825
3) Rs.4925
4) Rs.4025
5) Rs.4425
6) Rs.3220
7) Rs.4500
8) Rs.4525
9) Rs.4625
10) None of these

Solution

Suppose Anthony's gets Rs.100 then Akbar gets Rs.70
Amar gets = 15% more than Akbar = 70*115/100 = 80.5

Aamr:Akbar:Anthony = 80.5:70:100

Therefore Aamr's share = (80.5/250.5)*12525 = Rs. 4025
80% of 4025 = 3220
Option 6)

Correct Option: 6 Best Solution (0)

07 May 2018 Simple Interest

A person borrows Rs. 45000 for 4 years at 6.25% p.a. simple interest. He immediately lends it to another person at 9.75 p.a for 4 years. Find his gain in the transaction per year.

OPtion

1) 6300
2) 6500
3) 6100
4) 3150
5) 3050
6) 3350
7) 1575
8) 1550
9) 1600
10)None of these

Solution

SI on borrowing = 45000*4*6.25/100 = 11250

SI on Lending = 45000*4*9.75/100 = 17550


Gain per year = (17550 - 11250)/4 = 6300/4 = 1575

Option 7)

Correct Option: 7 Best Solution (0)

04 May 2018 Percentage

Goods and Service tax on bread increases its cost by 15%. To keep their budget in control a family reduces its bread consumption by 15%.
What is the percent increase or decrease in the expenditure of the money?

OPtion

1) 2.25% increase
2) 2.75% increase
3) 97.25% increase
4) 3.25% increase
5) 3.75% increase
6) 2.25% decrease
7) 2.75% decrease
8) 97.25% decrease
9) 3.25% decrease
10) None of these

Solution

Lets assume inital consumption of bread Rs. 100
Post GST cost would have become Rs. 115

Considering the family has redcued the consumption so their new expense without GST would be = 100*(100-15)/100 = Rs. 85

With 15% GST the actual cost of bread would be = 85*15/100 + 85 = 97.75

Considering inital cost was 100 and new cost is 97.75 so its a decrese in the expenditure
Decrease in expense = 100 - 97.75 = 2.25%

Correct Option: 6 Best Solution (0)

03 May 2018 Lift

Jack enters a lift on the 10th floor, which is going up @ 53 floors/min speed. At the same time Jill

enters another lift on the 370th floor which is going down @ 67 floors/min speed. At what floor will

they be together?

OPtion

1) 159
2) 149
3) 165
4) 161
5) 169
6) 167
7) 163
8) 171
9) 173
10) None of these

Solution

Relative Speed = 53+67 = 120 floors/min
Relative Distance = 370 - 10 = 360 floors

Time to cover 360 floors with relative speed = 120*60/360 = 180 seconds

Floors travelled by Jack in 180 seconds = (53/60)*180 = 159
Floors on which they will meet = 10 + 159 = 169th
Option 5)

Correct Option: 5 Best Solution (8)

02 May 2018 Work & Time

If 6 men and 8 women can do a piece of work in 10 days and 4 men and 7 women can do it in 12 days, how many days will 4 men and 12 women take to do half of work?

OPtion

1) 3.66
2) 7.50
3) 3.33
4) 3.00
5) 6.5
6) 7.0
7) 3.25
8) 6.75
9) 8.00
10) None of these

Solution

Let a man's daily work is x units and that of a woman is y units.
So total amount of work, W = 10(6x + 8y) = 12(4x + 7y)

Solving we get, 60x - 48x = 84y - 80y
=> 12x = 4y
=> y = 3x


Now, 6 x + 8 y can do work in 10 days.
So, 6x + 24x can do work in 10 days.
So, 30 x can do work in 10 days.

Now, 4x + 12y = 4x + 36x = 40x

Hence, if 30 x can do work in 10 days, 40x can do work in (10*30)/40 = 7.5 days.

Half of work would be done in = 7.50/2 = 3.75

Option 10)

Correct Option: 10 Best Solution (6)

01 May 2018 Age

A is 4 years older than B who is three times as old as C. The total of the ages of A, B and C is 88 years. What is the average of A and C ages?

OPtion

1) 26 years
2) 24 years
3) 30 years
4) 22 years
5) 20 years
6) 25 years
7) 28 years
8) 18 years
9) 32 years
10)None of these

Solution

Let’s assume Age of B be B years
Age of A = B+4
Age of C = B/3

Total age = B + 4 + B + B/3 = 88
Solving 7B/3 = 84
B = 12*3 = 36
A = B+4 = 40
C = B/3 = 12

Average = (40+12)/2 = 26 years

Option 1)

Correct Option: 1 Best Solution (0)

30 Apr 2018 Simple Interest

A sum of money at simple interest amounts to Rs. 7689 in 4 years and to Rs. 12654 in 14 years. The sum is:

OPtion

1) 5701
2) 5703
3) 5801
4) 5603
5) 5601
6) 5803
7) 5702
8) 5802
9) 5602
10) None of these

Solution

S.I. for 10 years = Rs. (12654 - 7689) = Rs. 4965
S.I. for 1 year = Rs. 4695/10


S.I. for 4 years = Rs. 4*(4965/10) = 1986
Principal = Rs. (7689 - 1986) = Rs. 5703

Correct Option: 2 Best Solution (0)

27 Apr 2018 LCM HCF

The HCF and LCM of two numbers is 14 and 588 respectively. If the first number is 84, find the second one?

OPtion

1) 88
2) 90
3) 92
4) 94
5) 80
6) 82
7) 98
8) 86
9) 96
10) None of these

Solution

LCM*HCF = a*b
14*588 = 84*b

=>b = 98

Correct Option: 7 Best Solution (0)

26 Apr 2018 Series

6, 9, 8, 11, 10, 13,....
What is the eighth term of following series?

OPtion

1) 12
2) 11
3) 13
4) 14
5) 15
6) 16
7) 17
8) 10
9) 18
10) None of these

Solution

This is a simple alternating addition and subtraction series. In the first pattern, 3 is added; in the second, 1 is subtracted.

So 13 -1 = 12 and 12+3 = 15

Option 5)

Correct Option: 5 Best Solution (0)