M4maths Previous Puzzles

29 Oct 2010 Mat dimension?

The dimensions of a room are 25 feet * 20 feet. The breadth of a mat is 5 feet.
How long mat (measured in feet) is required to cover the whole room by mat.

OPtion

1) 25
2) 20
3) 50
4) 100
5) 200
6) 500
7) 250
8) 120
9) 125
10) 9

Solution

length = 25 * 20 / 5 = 100

Correct Option: 4 Best Solution (1)

28 Oct 2010 What will be the next?

142 251 381 ?

OPtion

1) 527
2) 432
3) 421
4) 466
5) 436
6) 465
7) 454
8) 364
9) 463
10) 451

Solution

add the digit and its multiplication

142 = 1*4*2+(1+4+2) = 15 reverse is 51
first digit in increase by 1 251

251 = 2*5*1+(2+5+1) = 18 reverse the number 81
first digit in increase by 1 381

381 = 3*8*1+(3+8+1) = 36 reverse is 63
463

Correct Option: 9 Best Solution (0)

27 Oct 2010 Fine the best investment

A man buys 3 shirts, each of different brands. The shopkeeper gives him a discount of 10, 20 and 30 percent in
the 3 shirts according to the choice of buyer. If printed cost of shirts are 500, 800, 1200.
The minimum investment of the buyer will be

OPtion

1) 1910
2) 2030
3) 1970
4) 2040
5) 2070
6) 1960
7) 1890
8) 1870
9) 1930
10) 1920

Solution

For minimum investment 30 percent discount should be taken in the shirt of maximum cost, thus
Minimum investment = 1200 * 0.7 + 800 * 0.8 + 500 * 0.9 = 1930

Correct Option: 9 Best Solution (10)

26 Oct 2010 Find the number

What will be the difference between a number and its difference from the number itself?
Given that the number is square of square of a natural number.

OPtion

1) 100
2) 64
3) 25
4) 9
5) 36
6) 256
7) 121
8) 144
9) 0
10) 49

Solution

According to the given condition (1)
Difference = x-(x-x) = x
And according to the given condition (2), only 256 is valid.

Correct Option: 6 Best Solution (2)

25 Oct 2010 Relative Difference?

The cost of soap A is 18 rupee/200 gms. & that of another soap B is 10 rupee/100 gms.
How many % the cost of A is less relative to the cost of B?

OPtion

1) 11
2) 12.5
3) 5
4) 0
5) 9
6) 12
7) 25
8) 10
9) 2
10) 20

Solution

ost of A = 9 rupee/100 gms
Thus % = (1/10)*100 = 10

Correct Option: 8 Best Solution (6)

22 Oct 2010 Find the monthly Installment

A watch is available for Rs. 970 cash or Rs. 210 as cash down followed by three equal
monthly installments. If the rate of interest is 16% per annum, find the monthly Installment

OPtion

1) 240
2) 190
3) 245
4) 250
5) 255
6) 300
7) 260
8) 195
9) 200
10) 265

Solution

The 3 installment are equal, thus
A = (P1)[1+(16/1200)]^1 = (P1)[1216/1200]^1
Implies that (P1) = [1200/1216]^1*A
A = (P2)[1+(16/1200)]^2= (P2)[1216/1200]^2
Implies that P2 = [1200/1216]2A
A = (P3)[1+(16/1200)]^3= (P3)[1216/1200]^3
Implies that (P3) = [1200/1216]^3*A
(P1) + (P2) + (P3) = [1200/1216]^1*A + [1200/1216]^2*A + [1200/1216]^3*A
760 = [1200/1216]^1*A + [1200/1216]^2*A + [1200/1216]^3*A
A = 760/ [1200/1216]^1 + [1200/1216]^2 + [1200/1216]^3
A = 260.12 ~ 260

Correct Option: 7 Best Solution (2)

21 Oct 2010 find the probability of monday?

What is the probability that at any date such as 01/01/1952, there is Monday ?

OPtion

1) 1/2
2) 2/7
3) 3/7
4) 1/3
5) 1/30
6) 1/12
7) 1/52
8) 1/26
9) 1/13
10) 1/7

Solution

There are 7 days in a week and only one Monday
Hence probability = 1/7

Correct Option: 10 Best Solution (3)

20 Oct 2010 How many days required?

Ram is double efficient than Shyam. Shyam is thrice efficient than Arjun. Arjun is half efficient than Mohan.
They start a work together. In how many days the work will be completed, if only Shyam completes it in 20 days.

OPtion

1) 16
2) 6
3) 8
4) 10
5) 12
6) 14
7) 15
8) 5
9) 18
10) 2

Solution

One day work of Shyam = 1/20 part
Similarly that of Ram, Arjun and Mohan are 2/20, 1/60, 1/30 parts respectively according to the given conditions.
Total one day work = (2/20) + (1/20) + (1/60) + (1/30) = 12/60
No. of days required = 60/12 = 5

Correct Option: 8 Best Solution (7)

19 Oct 2010 Fine the Probability?

A dice is thrown once. Find the probability of getting a number greater then 2.

OPtion

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

Solution

Total possible cases = 6
Numbers greater than 2 on the dice = (3,4,5,6)
So Probability of getting a number > 2 =4/6=2/3

Correct Option: 2 Best Solution (7)

18 Oct 2010 Find the instalment

A loan of Rs. 48,800/- is to be paid back in three equal annual instalments. If the rate of
interest is 25% per annum compounded annually, find the instalment.

OPtion

1) 23000
2) 12000
3) 20000
4) 25000
5) 24500
6) 25600
7) 23800
8) 24800
9) 28000
10) 22000

Solution

Let the instalment be Rs x
Present values of 1st, 2nd and 3rd instalments are
are (4/5)x, (4/5)^2x, (4/5)^3x
so (4/5)x [1 + 4/5 + 16/25] = 48800
OR x = 25000
so each instalment = Rs. 25000

Correct Option: 4 Best Solution (7)