M4maths Previous Puzzles

01 Mar 2017 Interest

The difference between simple and compound interests compounded annually on a certain sum of money for 4 years at 6.5% per annum is Rs. 1191. The value of the sum (approximately) is:

OPtion

1) 40000
2) 40500
3) 41000
4) 41500
5) 42000
6) 44500
7) 43000
8) 43500
9) 42500
10)None of these

Solution

Let the sum be Rs. X

CI = [x(1+6.5/100)^4] – x = x*(106.5/100)^4 – x
SI = x*4*6.5/100
CI-SI = x*(106.5/100)^4 – x - x*26/100 = 1.2865x – x – 0.26x = 0.265x
As per question CI-SI = 1191
So 0.265x = 1191 => x = Rs. 45000

Option 10)

Correct Option: 10 Best Solution (5)

28 Feb 2017 Age Problem

The present ages of A,B and C are in proportions 4:5:6. Eight years ago, the sum of their ages was 66. What is the sum of present age of A and C?

OPtion

1) 48 years
2) 50 years
3) 52 years
4) 54 years
5) 56 years
6) 58 years
7) 60 years
8) 62 years
9) 64 years
10)66 years

Solution

Eight years ago sum of Ages of A, B and C = 66
Eight years later i.e. sum of current ages of A, B and C = 66+(3*8) = 90
Present Age of A = 90*4/(4+5+6) = 4*6 = 24 years
Present Age of c = 90*6/(4+5+6) = 6*6 = 36 years
Sum = 24+36 = 60 years

Option 7)

Correct Option: 7 Best Solution (31)

27 Feb 2017 Series

1, 1, 2, 3, 5, 8, 13, .....
Sum of 9th and 10th terms of above series is:

OPtion

1) 21
2) 34
3) 45
4) 55
5) 72
6) 87
7) 89
8) 91
9) 144
10)None of these

Solution

First 10 Fibonacci series:
1, 1, 2, 3, 5, 8, 13, 21, 34, 55
Sum of 9th and 10th term = 34 + 55 = 89

Option 7)

Correct Option: 7 Best Solution (14)

24 Feb 2017 Ratio

If a/b = 1/3, b/c = 1/2, c/d = 6/7,e/f = 14/9 and d/e = 7/2 and, then what is the value of abc/def ?

OPtion

1) 1/14
2) 3/14
3) 1/7
4) 3/7
5) 1/9
6) 2/9
7) 6/7
8) 2/21
9) 7/9
10)None of these

Solution

a/d = (a/b)*(b/c)*(c/d) = (1/3)*(1/2)*(6/7) = 1/7
b/e = (b/c)*(c/d)*(d/e) = (1/2)*(6/7)*(7/2) = 3/2
c/f = (c/d)*(d/e)*(e/f) = (6/7)*(7/2)*(14/9) = 14/3

So abc/def = (a/d)*(b/e)*(c/f) = (1/7)*(3/2)*(14/3) = 1

Option 10)

Correct Option: 10 Best Solution (10)

23 Feb 2017 Rank of word

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

OPtion

1) 62219
2) 62220
3) 62229
4) 62230
5) 62239
6) 62240
7) 62249
8) 62250
9) 62259
10)None of these

Solution

SHIVRATRI => AHIIRRSTV
Arranging letters in alphabetical order: AHIIRRSTV => I and R are repeated (2 I’s& 2 R’s)
Words starting with Alphabet A = 8!/(2!*2!) = 10080
Words starting with Alphabet H = 8!/(2!*2!) = 10080
Words starting with Alphabet I = 8!/2! = 20160
Words starting with Alphabet R = 8!/2! = 20160
Words starting with Alphabet SA = 7!/(2!*2!) = 1260
Words starting with Alphabet SHA = 6!/(2!*2!) = 180
Words starting with Alphabet SHIA = 5!/2! = 60
Words starting with Alphabet SHII = 5!/2! = 60
Words starting with Alphabet SHIR = 5! = 120
Words starting with Alphabet SHIT = 5!/2! = 60
Words starting with Alphabet SHIVA = 4!/2! =12
Words starting with Alphabet SHIVI = 4!/2! = 12
Words starting with Alphabet SHIVRAI = 2! = 2
Words starting with Alphabet SHIVRAR = 2! = 2
Words starting with Alphabet SHIVRATI = 1 = 1
And next word is SHIVRATRI so +1 for final word
Sum of all words => 2*10080 + 2*20160 + 1260 + 180+ 3*60 + 120 + 2*12 + 2*2 + 1 + 1 =62250

Option 8)

Correct Option: 8 Best Solution (2)

22 Feb 2017 Find the value

Find the value of x^2 - 3x/2 - 4
Given equation:
(3!)^2 - (2!)^1 - (1!)^0 - 3! - 2! - 1! - 0! = 7 + x^2

OPtion

1) 0
2) 1
3) 2
4) 3
5) 4
6) 5
7) 6
8) 7
9) 8
10)None if these

Solution

Given
(3!)^2 - (2!)^1 - (1!)^0 - 3! - 2! - 1! - 0! = 7 + x^2
=>x^2 = 6^2 - 2 - 1 - 6 - 2 - 1 - 1 - 7
=>x^2 = 16
=> x = 4
So x^2 - 3x/2 - 4= 16 - (3/2)*4 - 4 = 16 - 6 - 4 = 6

Correct Option: 7 Best Solution (20)

21 Feb 2017 Simple Interest

A sum of Rs. 4321 amounts to Rs. 6481.5 in 8 years at the rate of simple interest. What is the rate of interest?

OPtion

1) 5.5 %
2) 5.75 %
3) 6.0 %
4) 6.25 %
5) 6.5 %
6) 6.75 %
7) 7.0 %
8) 7.25 %
9) 7.5 %
10)None of these

Solution

S.I. = Rs. (6481.5 - 4321) = Rs. 2160.5

Rate = (2160.5*100)/(4321*8)

Rate = (555.5*100)/(1111*4) = 100/16 = 6.25 %
Option 4)

Correct Option: 4 Best Solution (25)

20 Feb 2017 Age Problem

Sum of the ages of a boy and his father is 77 years. Before 22 years Father's age was 10 times the age of the boy. What was the age of father at the time of birth of the child?

OPtion

1) 23 Years
2) 24 Years
3) 26 Years
4) 27 Years
5) 28 Years
6) 29 Years
7) 30 Years
8) 31 Years
9) 32 Years
10)33 Years

Solution

Let the present age of father and son be x and y respectively
According to the given condition
x+y = 77 ---- (i)
before 22 years
(x-22) = 10(y-22)
Replacing value of x from equation (i)
so 77-y-22 = 10(y-22)
=> 55-y = 10y-220
=> 11y = 275
=> y = 25 and x = 52
so at the time of birth of child, age of father = 52-25 = 27 years

Option 4)

Correct Option: 4 Best Solution (23)

17 Feb 2017 Profit and Loss

A vendor bought 90 chocolates for 180 rupees. How many chocolates in 180 rupees must he sell to gain 25%?

OPtion

1) 60
2) 65
3) 66
4) 68
5) 70
6) 72
7) 75
8) 80
9) 82
10)None of these

Solution

CP of 1 Chocolate = 180/90 = Rs. 2
SP of 1 Chocolate for 25% profit = 2*1.25 = Rs. 2.5
So in 180 Rupess how many chocolates should be sold = 180/2.5 = 72

Option 6)

Correct Option: 6 Best Solution (13)

16 Feb 2017 CODING-DECODING

If TATANAGAR is coded as: 6890 and GHAZIABAD as: 3482 then what is the code for DARJEELING?

OPtion

1) 3600
2) 4225
3) 6084
4) 7226
5) 7396
6) 7596
7) 8281
8) 8464
9) 8649
10)None of these

Solution

A=1, B=2, C=3, D=4……. Z=26

Each string is coded as = Square of (Sum of all alphabets) +1

So for DARJEELING = (4+1+18+10+5+5+12+9+14+7)^2+1 = 85^2 +1 = 7225 +1 = 7226

Option 4)

Correct Option: 4 Best Solution (3)