M4maths Previous Puzzles

01 Aug 2018 Fraction

If a/b = 19/3, b/c = 15/26, c/d = 13/19, e/f = 7/117 and d/e = 19/25 then what is the value of (abc/def)*5 ?

OPtion

1) 1
2) 1/2
3) 1/3
4) 7/225
5) 11/60
6) 5/60
7) 8/60
8) 7/60
9) 8/45
10) None of these

Solution

a/d = (a/b)*(b/c)*(c/d) = 5/2
b/e = (b/c)*(c/d)*(d/e) = 3/10
c/f = (c/d)*(d/e)*(e/f) = 7/225

So 5*abc/def = 5*(a/d)*(b/e)*(c/f) = 5*(5/2) *(3/10) * (7/225) = 7/60

Option 8)

Correct Option: 8 Best Solution (10)

31 Jul 2018 Probability

If two letters are taken at random from the word CANE, what is the probability that none of the letters would be vowels?

OPtion

1) 2/5
2) 3/5
3) 1/2
4) 1/6
5) 1/3
6) 1/12
7) 2/3
8) 3/4
9) 5/12
10) None of these

Solution

P(first letter is not vowel) = 2/4

P(second letter is not vowel) = 1/3

So, probability that none of letters would be vowels is = 2/4×1/3=1/6

Correct Option: 4 Best Solution (8)

30 Jul 2018 Series

What is the next term of following series:
5, 8, 13, 20, 29,

OPtion

1) 50
2) 35
3) 30
4) 36
5) 40
6) 42
7) 45
8) 38
9) 34
10) None of these

Solution

nth term = n^2 + 4
n=1, 2, 3, 4, 5, 6, and so on

So 6th term = 6^2 + 4 = 40

Option 5)

Correct Option: 5 Best Solution (7)

27 Jul 2018 Remembering APJ Abdul Kalam!

Find Rank of the word APJABDUL in the dictionary of words formed by the letters of the word APJABDUL

OPtion

1) 3928
2) 3926
3) 3959
4) 3955
5) 3947
6) 3948
7) 3962
8) 3961
9) 3938
10) None of these

Solution

RANK is:3962

5*6! + 3*5! + 1*1! +1 = 3962

Correct Option: 7 Best Solution (3)

26 Jul 2018 Standard Deviation

Marks of Raj, Ram, Rohan, Ahmed, Akash, Akram, Mohit, Raju, Mohan, Ricky and Rahul who are students of a coaching institute are: 73 64 74 81 77 71 75 78 59 72 and 74 respectively.

What is the population standard deviation of their marks?

OPtion

1) 5.89
2) 5.39
3) 5.59
4) 5.99
5) 5.91
6) 6.25
7) 5.81
8) 5.96
9) 6.19
10)None of these

Solution

Mean of 11 marks = 798/11 = 72.54
Sum of squared difference from mean for each number = (73-72.6)^2 + (64-72.6)^2 + ......+ (74-72.6)^2 = 390.76

Average of Squared difference (Variance) = 390.76/11 = 35.52
Population Standard Deviation = Square root of variance = 35.52^1/2 = ~5.96

Option 8)

Correct Option: 8 Best Solution (5)

25 Jul 2018 Simple Interest

A person borrows Rs. 29000 each from 2 lenders for 7 years at 6.75% p.a. simple interest. He immediately lends both the sums to another person at 11.25 p.a for 7 years. Find his gain in the transaction per year.

OPtion

1) 4567.5
2) 1305
3) 18270
4) 45675
5) 9235
6) 9335
7) 1805.5
8) 1306
9) 1300
10)None of these

Solution

SI on borrowing = 2*29000*7*6.75/100 = 27405


SI on Lending = 2*29000*7*11.25/100 = 45675


Gain per year = (45675- 27405)/7 = 2610

Option 10)

Correct Option: 10 Best Solution (3)

24 Jul 2018 Age

A is 11 years older than B who is three times as old as C. The total of the ages of A, B and C is 123 years. What is the value when the age of B is added to the difference between ages of A and C ?

OPtion

1) 64 years
2) 77 years
3) 82 years
4) 85 years
5) 43 years
6) 90 years
7) 91 years
8) 84 years
9) 101 years
10)None of these

Solution

Let’s assume Age of B be B years
Age of A = B+11
Age of C = B/3

Total age = B + 11 + B + B/3 = 123
Solving 7B/3 = 112
B = 48
A = B+11 = 59
C = 48/3 = 16


Difference between ages of A and C = (59-16) = 43

Final Value = Age of B + Diff of Age of A and C = 48 + 43 = 91

Option 7)

Correct Option: 7 Best Solution (9)

23 Jul 2018 Simple Interest

At what simple interest rate percent per annum will a sum of money double in 9 years.

OPtion

1) 22.22
2) 12.00
3) 10.33
4) 11.11
5) 12.25
6) 11.25
7) 11.50
8) 11.75
9) 12.11
10) None of these

Solution

SI = PRT/100

SI = P

So P = P*R*9/100
= R= 100/9 = 11.11
Option 4)

Correct Option: 4 Best Solution (6)

20 Jul 2018 Arithmatic

If the number of boys in a class is 6 times the number of girls, which value can never be the total number of students?

OPtion

1) 42
2) 56
3) 28
4) 140
5) 84
6) 48
7) 70
8) 63
9) 98
10) None of these

Solution

Let number of girls be x

So number of boys = 6x


Then, total number of students = x+6x 7x

i.e., total number of students must be a multiple of 7

In the given choices, 48 is not a multiple of 7

Correct Option: 6 Best Solution (8)

19 Jul 2018 Code Decode

If "Die with memories, not dreams" is coded as 3249532 and "Love For All, Hatred For None" is coded as 144288144 then what is the code for "Tough times never last but tough people do"

OPtion

1) 63675140000
2) 63675148000
3) 63675340000
4) 63675940000
5) 63675048000
6) 63675640000
7) 63675740000
8) 63675840000
9) 63675040000
10) None of these

Solution

Each alphabet is coded as A=26, B=25, C= 24...Z=1

Code is formed by: multiplication of highest numbered letter of each word

So Die with memories, not dreams" = =23*19*22*13*26 = 3249532 and
Love For All, Hatred For None = =22*21*26*26*21*22 = 144288144

Similarly for Tough times never last but tough people do = =20*22*22*26*25*20*22*23 = 63675040000

Option 9)

Correct Option: 9 Best Solution (0)