M4maths Previous Puzzles

15 Oct 2010 Find the probability?

A man has 3 children. Their probabilities of passing an exam are 1/2, 1/3, 1/4.
What will be the probability that at least 1 of them could pass the exam?

OPtion

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

Solution

The probability of failure of all = [1-(1/2)][1-(1/3)][1-(1/4)] = 1/4
Hence answer = [1-(1/4)] = 3/4

Correct Option: 3 Best Solution (2)

14 Oct 2010 Possible solution?

The total cost of 1 copy and 2 pencils is 10 rupee. How many non zero integral solutions are possible
for the cost of a copy and a pencil.

OPtion

1) 4
2) 3
3) 2
4) 1
5) 5
6) 6
7) 7
8) 8
9) 9
10) 0

Solution

Solutions are (2,4), (4,3), (6,2), (8,1)

Correct Option: 1 Best Solution (9)

13 Oct 2010 A.P series

Which term of the A.P. 3, 14, 25, 36.... is 121 more than its 82th term ?

OPtion

1) 110
2) 89
3) 83
4) 93
5) 62
6) 86
7) 94
8) 91
9) 99
10) 103

Solution

Here a = 3 , d = 11
So t(54) = 3 + (82 —1).11 = 894
Let n be number of terms
So t(n) = 894 + 121 = 1015
=> 3 + ( n—1).11 = 1015
=> n = 93

OR

121/11 = 11
so that term would be
82+11 = 93

Correct Option: 4 Best Solution (7)

12 Oct 2010 number and its cube

A number is equal to four times of its cube, the number is

OPtion

1) .02
2) .4
3) .8
4) .6
5) .9
6) .5
7) .05
8) .08
9) .3
10) .2

Solution

According to the given condition x = 4 x^3
On solving we get, x = 0.5

Correct Option: 6 Best Solution (0)

11 Oct 2010 Find the value of B

If A + B = 1 and (x — 2) is a factor of x2 + Ax + B, find the value of B

OPtion

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

Solution

(x - 2) is a factor of x^2 +Ax + B
so 4 + 2A + B = 0
=> 2A + B = -4
also A+B=1
Solving to get A = -5
B = 6

Correct Option: 7 Best Solution (12)

08 Oct 2010 Find the number

The sum of the squares of two positive integers is 208. If the square of the larger number is 18 times the smaller,
find the smaller number.

OPtion

1) 1
2) 22
3) 3
4) 4
5) 15
6) 6
7) 8
8) 7
9) 10
10) 12

Solution

Let two postive numbers be x & y and x > y
X^2 + Y^2 = 208 .....................................(i)
X^2 = 18y ................................................(ii)

Y^2 + 18y - 208 = 0
=>(y+26) ( y-8)=0
=> y= -26 or y =8
Putting Y = 8 in (ii) X = 12, X= -12 (false)
X = 12, Y = 8

Correct Option: 7 Best Solution (0)

07 Oct 2010 Rate Of intrest

A suit is available for Rs. 1500 cash or for Rs. 500 cash down payment followed by 3 monthly installments of
Rs. 345 each. Find the rate of interest charged under the installment scheme.

OPtion

1) 24.76
2) 19.67
3) 37.23
4) 21
5) 21.31
6) 78.65
7) 22.73
8) 13.1
9) 12.31
10) 23.9

Solution

Cash Price = 1500
Price under Installment Plan = 500 + 1035 = 1535
Interest Charged = Rs. 35
Principal for each month = 1000 + 655 + 310
∴ Total Principal = Rs. 1965
Rate = (35 * 100 * 12)/(1965 * 1)=2800/131 = 21.31% approx

Correct Option: 5 Best Solution (1)

06 Oct 2010 Time and work

Ram completes a work in 10 days. Ram and Ashok together take 6 days to complete the same work.
Days taken by Ashok to do the same work are?

OPtion

1) 14
2) 12
3) 10
4) 8
5) 9
6) 15
7) 16
8) 18
9) 20
10) 21

Solution

Let the days taken by Ashok be x, then (1/x) + (1/10) = (1/6)

Correct Option: 6 Best Solution (4)

05 Oct 2010 Share market

Kumar bought 100 shares at a rate of 98.50 per share and sold these shares at a rate of 99.35 per share.
Brokerage is 4 paisa per 100 rupee. Total brokerage in the whole transaction is

OPtion

1) 8.45
2) 6.56
3) 7.92
4) 9.49
5) 5.46
6) 6.78
7) 7.59
8) 8.67
9) 9.13
10) 5.42

Solution

Brokerage = (98.5+99.35)* 100* 0.04/100 = 197.85* 0.04 = 7.92

Correct Option: 3 Best Solution (6)

04 Oct 2010 4 digit number

The sum of a number of 4 digit having successive digits in increasing order and number formed
by taking these 4 digits in reverse order is 12221. Find the number.

OPtion

1) 8765
2) 7654
3) 2345
4) 5432
5) 5678
6) 4567
7) 6789
8) 9876
9) 3456
10) 6543

Solution

{1000x+100(x+1)+10(x+2)+x+3}+{1000(x+3)+100(x+2)+10(x+1)+ x} = 12221
Hence x =4, number is 4567

Correct Option: 6 Best Solution (14)