M4maths Previous Puzzles

10 May 2012 pen and note book

The cost of 4 pens is same as that of 1 note book. The total cost of x pens and x/2 note books is 150 rupee. The maximum possible cost of the pen will be (in rupee)

OPtion

1) 10
2) 20
3) 25
4) 30
5) 40
6) 50
7) 60
8) 65
9) 70
10) none of these

Solution

according to the given condition
x pen = x/4 note book
so x/4 + x/2 = 3x/4 note book costs 150 rupee
so cost of 1 note book = 150*4/3x = 200/x
and that of pen = 50/x
now there are x/2 note books so minimum value of x will be 2
so minimum cost of pen = 50/2 = 25

Correct Option: 3 Best Solution (8)

09 May 2012 bags

There are 2 bags. The first contains 8 white, 4 red and 6 green balls whereas second contains 6 white, 8 red and 4 black balls. One ball from both the bag is selected, then probability to get the balls of same colour will be

OPtion

1) 4/27
2) 8/81
3) 16/81
4) 32/81
5) 16/27
6) 8/27
7) 20/81
8) 10/81
9) 1/81
10) none of these

Solution

If white is selected from both the bags then probability = 8/18*6/18
if red is selected from both the bags then probability = 4/18*8/18
sum of these two will be the answer.

Correct Option: 7 Best Solution (11)

08 May 2012 sum sum

The sum of three positive real numbers x, y and z is 9. If the largest positive difference between any 2 of the 3 numbers is 5 and these 3 numbers are in arithmetic progression then the product of these 3 numbers will be

OPtion

1) 15
2) 24
3) 105/4
4) 81/4
5) 33/4
6) 18
7) 429/16
8) 99/4
9) 125/4
10) none of these

Solution

x+y+z = 9
and the three are in AP so y = 3
so x+z = 6
and z-x = 5 consider that z is the greatest and x is least number
on solving these 2 equations we get x = 1/2, y = 3, z = 11/2

Correct Option: 5 Best Solution (0)

07 May 2012 series

next number of the series
1.2 + 2.16 + 5.184 + 15.552 + ................. will be

OPtion

1) 46.8766
2) 55.9872
3) 58.9682
4) 58.9932
5) 64.4532
6) 68.7764
7) 72.3332
8) 76.9682
9) 77.8972
10) none of these

Solution

The series is
1.2
1.2*1.8
1.2*1.8*2.4
1.2*1.8*2.4*3.0
1.2*1.8*2.4*3.0*3.6

Correct Option: 2 Best Solution (13)

04 May 2012 ratio

Ratio of 3 positive numbers x, y and z is 2:3:4 and the ratio of 3 positive numbers p, q and r is 1:2:3. By using these 2 ratios a new ratio is formed as 13:j:31. j will be

OPtion

1) 14
2) 15
3) 16
4) 18
5) 20
6) 22
7) 24
8) 25
9) 28
10) none of these

Solution

the new ratio is obtained by 4F+5S
so first number of the new ratio = 4(2)+5(1) = 13
similarly others

Correct Option: 6 Best Solution (0)

03 May 2012 natural numbers

Three natural numbers x, y and z are such that x + y^2 + z^3 = 15
How many set of values of x, y and z are possible.

OPtion

1) 1
2) 2
3) 3
4) 4
5) 5
6) 6
7) 7
8) 8
9) 9
10) none of these

Solution

For z only 1 and 2 are possible values so
13, 1, 1
10, 2, 1
5, 3, 1
6, 1, 2
3, 2, 2

Correct Option: 5 Best Solution (7)

02 May 2012 words words

How many words can be formed by using the letters of the word WEDNESDAY
(all meaningful and meaningless words are acceptable)

OPtion

1) 90720
2) 362880
3) 181440
4) 45360
5) 22680
6) 11340
7) 720
8) 1440
9) 2880
10) none of these

Solution

total letters = 9
revised letters are E and D, both are revised twice
so total possible words = 9*8*7*6*5*4*3*2*1/2*2 = 90720

Correct Option: 1 Best Solution (6)

01 May 2012 hours ho hours

Total number of hours we have spent upto the time of getting puzzle today starting from the start of this year

OPtion

1) 2845
2) 2867
3) 2895
4) 2904
5) 2909
6) 2913
7) 2915
8) 2923
9) 2954
10) none of these

Solution

Total number of days upto 30th april = 121
so hours = 121*24 = 2904
and 11 hours of may so total hours = 2904+11 = 2915

Correct Option: 7 Best Solution (16)

30 Apr 2012 odd one out

select the one unmatched number

OPtion

1) 133
2) 171
3) -57
4) -114
5) 38
6) -51
7) -171
8) -76
9) 95
10) none of these

Solution

all numbers are multiple of 19 other than -51

Correct Option: 6 Best Solution (14)

27 Apr 2012 power of 2

solve 32^(3/10) * 8^(5/6)

OPtion

1) 1
2) 2
3) 4
4) 8
5) 16
6) 32
7) 64
8) 128
9) 256
10) none of these

Solution

32^(3/10) = 2sqrt(2)
8^(5/6) = 4sqrt(2)
so product = 16

Correct Option: 5 Best Solution (16)