M4maths Previous Puzzles

24 Dec 2010 Find the value of X

Difference of a number and its square is equal to the difference of its square and 1 less than twice
of the number. Product of the values of x is

OPtion

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

Solution

x – x2 = x2 – (2x-1)

On solving this equation we get x = 1, 1/2

Correct Option: 6 Best Solution (6)

23 Dec 2010 Probability

There are two bags. First contains 7 red and 5 violet balls whereas second contains 7 violet and 5 red balls.
A ball is drawn at random from both the bags. Probability of both balls having same colour is

OPtion

1) 25/49
2) 35/144
3) 1/2
4) 5/7
5) 35/72
6) 7/25
7) 3/5
8) 1/9
9) 49/72
10) 28/99

Solution

(7/12)*(5/12) + (5/12)*(7/12) = 70/144 = 35/72

Correct Option: 5 Best Solution (10)

22 Dec 2010 Next Number

1, 60, 60, 24, 7, 4.5 ............
Next number will be

OPtion

1) 8
2) 14
3) 10
4) 12
5) 16
6) 17
7) 7
8) 20
9) 31
10) 18

Solution

The sequence is
1 second

1 minute = 60 seconds

1 hour = 60 minutes

1 day = 24 hours

1 week = 7 days

1 month = 4.5 weeks

1 year = 12 months

Correct Option: 4 Best Solution (4)

21 Dec 2010 share market

A man buys 1000, 2000 and 3000 shares of 3 companies respectively. Buying price of these 3 shares are 58, 72 and 45.
If he sells these 3 shares in 62, 70 and 46 rupee per share respectively. Then total profit or loss will be-

(These prices include all types of taxes and brokerage too)

OPtion

1) P, 3000
2) L, 3000
3) P, 4000
4) L, 4000
5) P, 5000
6) L, 5000
7) P, 2000
8) L, 2000
9) P, 1500
10) L, 1500

Solution

Total investment = 1000 * 58 + 2000 * 72 + 3000 * 45

= 58000 + 144000 + 135000 = 337000

Total output = 1000 * 62 + 2000 * 70 + 3000 * 46

= 62000 + 140000 + 138000 = 340000

Total profit = 140000 – 137000 = 3000

Correct Option: 1 Best Solution (8)

20 Dec 2010 Fine the average

The average of 10 numbers is 10.9 and that of higher 4 numbers among these 10 numbers is 11.5.
Average of lower 6 numbers will be

OPtion

1) 10.3
2) 10.6
3) 10.7
4) 10.8
5) 10.4
6) 10.5
7) 10.2
8) 10.1
9) 10
10) 9.9

Solution

Sum of all the 10 numbers = 10.9 * 10 = 109
Sum of higher 4 numbers = 11.5 * 4 = 46
Sum of lower 6 numbers = 109 – 46 = 63
Average = 63 / 6 = 10.5

Correct Option: 6 Best Solution (13)

18 Dec 2010 Probability?

There are 100 students in a class. 20 students are failed in chemistry whereas 3 are failed in mathematics and chemistry .
What will be the probability that any student failed in chemistry would also be failed in mathematics?

OPtion

1) 1/5
2) 3/100
3) 3/20
4) 3/5
5) 23/100
6) 3/10
7) 1/15
8) 4/13
9) 1/100
10) 3/2000

Solution

Required probability = p (M∩C)/p (M) = 3/20

Correct Option: 3 Best Solution (6)

17 Dec 2010 Time and work

A wall can be formed in a fix number of days by using 80 labours working 8 hours in a day.
How many labours are required to form the same wall in same number of days, if they work for 10 hours a day?

OPtion

1) 64
2) 68
3) 72
4) 81
5) 90
6) 100
7) 60
8) 54
9) 48
10) 52

Solution

80 * 8 = x * 10

Hence x = 64

Correct Option: 1 Best Solution (15)

16 Dec 2010 Chair problem

In a particular department 140 chairs are required. There is a scheme in the purchasing of chairs.
1. 1 chair is free in the purchasing of 1 dozen chairs.
2. There is a discount of 100 rupee in the purchasing of 1/2 dozen chairs.
If cost of 1 chair is 800 rupee, then total investment is

OPtion

1) 104000
2) 101900
3) 103900
4) 96000
5) 112000
6) 109000
7) 98400
8) 98900
9) 99800
10) 102800

Solution

Cost of 10 dozen chairs = 120 * 800 = 96000

Cost of free 10 chairs = 0
Cost of 10 chairs = 8000

Total discount in 10 and 1/2 dozens = 2100

Hence investment = 101900

Correct Option: 2 Best Solution (0)

15 Dec 2010 perfect square

How many consecutive terms (minimum no. of terms without leaving any of the term starting from first term)
of the sequence given below are required to make the product, a perfect square?
1, 3, 5, 6, 8, 9, 10, 12, 15, 20, 24, 48, 72, 100, 124, 150, 200, 240, 300, 500,

OPtion

1) 12
2) 10
3) 11
4) 9
5) 13
6) 14
7) 15
8) 16
9) 17
10) 18

Solution

The product of first 12 terms of the sequence is a perfect square.

Correct Option: 1 Best Solution (4)

13 Dec 2010 Perfect square

3 numbers are such that their product is perfect square. Set will be

OPtion

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

Solution

check that 12*9*3 = 9*12*3 = 9*36 = perfect square

Correct Option: 6 Best Solution (21)