M4maths Previous Puzzles

15 Oct 2020 Number of Cans

Chintu works at a soft drink company and was arranging some particular number of cylindrical aluminium soft drink cans in a square box but the box became full and there were 14 cans remaining to be put in. Then, he started arranging all Cans in a rectangular box where he could arrange 8 cans more along the length than the breadth after putting all the cans in the rectangular box. He found out that there was still space left for another 9 cans. What is the number of cans Chintu had if it is known that the number of cans were more than 10 and no can was put on top of another can?

OPtion

1) 44
2) 25
3) 16
4) 39
5) 36
6) 33
7) 45
8) 40
9) 43
10) None of these

Solution

In a square box the number of cans arranged along the length and breadth would be same.
In case of rectangular box, lets assume that number of cans along breadth is x then number of boxes along the length would be x+6
Total number of cans the rectangular box can take = x*(x+8)
Total number of cans Chintu was able to put in the rectangular box (as some empty space was remaining ) = x*(x+8) - 9 --- (i)


Given that the number of cans are more than 10, hence 2 & 3 cans along the length are ruled out

Lets try with 4 cans along length of square box, total cans in box would be 16
Total number of cans which Chintu has = 16+14 = 30 ---- (ii)
(i = (ii)
x*(x+8) - 9 = 30
=> x^2 + 8x = 39
Trying to solve we realize that there is no such whole number which x can take

Lets try with 5 cans along length of square box, total cans in box would be 25
Total number of cans which Chintu has = 25+14 = 39 ---- (ii)
(i = (ii)
x*(x+8) - 9 = 39
=> x^2 + 8x = 48
Solving we get x = 4

So total number of cans which Chintu had = x*(x+8) - 9 = 4(4+8) - 9 = 39

Correct Option: 4 Best Solution (1)

14 Oct 2020 Decode

If SWEET = 65337 and SALTY = 64179 then the code for TASTY would be =?

OPtion

1) 71679
2) 72679
3) 74619
4) 74879
5) 74678
6) 74679
7) 74579
8) 74379
9) 74179
10) None of these

Solution

AS SWEET is coded as "65337" and SALTY is coded as "64179"
So S is coded as 6, W as 5, E as 3, T as 7
and A as 4, L as 1, T as 7, Y as 9

So code for TASTY would be = 74679

Correct Option: 6 Best Solution (0)

13 Oct 2020 Speed

Fatafat express train traveling at 90 kmph crosses a platform in 30 seconds and a person standing on the platform in 18 seconds. What is the length of the platform in meters?

OPtion

1) 400
2) 350
3) 200
4) 300
5) 250
6) 275
7) 280
8) 325
9) 390
10) None of these

Solution

Length of the platform = speed of train * extra time taken to cross the platform.
Length of platform = 90 kmph * 12 seconds

Convert 90 kmph into m/sec
1 kmph = 5/18 m/s
∴ 72 kmph = 5/18∗90 = 25 m/sec

Therefore, length of the platform = 25 m/s * 12 sec = 300 meters.

Correct Option: 4 Best Solution (0)

12 Oct 2020 Profit & Loss

Find the cost price of 1KG of Lotus seeds which is sold for Rs. 819 at a loss of 9%.

OPtion

1) 780
2) 770
3) 860
4) 800
5) 909
6) 1000
7) 900
8) 1100
9) 880
10) None of these

Solution

If CP 100 SP 91
i.e. When SP 91, CP 100
when SP 819, CP = 100*819/91 = 900

Correct Option: 7 Best Solution (0)

09 Oct 2020 Find the value of

If
6x - 4y = 8
8x = 5y + 13
Then what is the value of 6x -3y?

OPtion

1) 18
2) 21
3) 12
4) 16
5) 15
6) 6
7) 8
8) 9
9) 10
10) None of these

Solution

6x - 4y = 8 ---- (i)
8x - 5y = 13 ---- (ii)

Subtracting (i) from (ii), we get: 2x - y = 5
Multiplying both sides by 3 we get 6x -3y = 15

Option 3)

Correct Option: 5 Best Solution (1)

08 Oct 2020 Work and Time

Rohit and Virat, working together, can complete an assigned task in 20 days. If Rohit worked alone and completes half the task and then Virat takes over and completes the remaining half, then the task gets completed in 45 days. How long will Rohit take to complete the task if he worked alone? Assume that Rohit is more efficient than Virat.

OPtion

1) 25
2) 20
3) 35
4) 36
5) 18
6) 30
7) 45
8) 50
9) 60
10) None of these

Solution

Let Rohit take 'x' days to complete the task if he worked alone.

Let Virat take 'y' days to complete the task if she worked alone.

Given that They will complete the task in 20 days, if they worked together.

In 1 day, Rohit will complete 1/x of the task.

In 1 day, Virat will complete 1/y of the task.

Together, in 1 day they will complete 120 of the task.

Therefore,1/x + 1/y = 1/20 .... (1)


As per question if Rohit worked alone and completed half the work and then Virat takes over and completes the second half, the task will be completed in 45 days.

Rohit will complete half the task in x/2 days.

Virat will complete half the task in y/2 days.

∴ x/2 + y/2 = 45

Or, x + y = 90 or x = 90 - y .... (2)


Solving 1 and 2 we get
y^2 - 90y + 1800 = 0

=> y 30 or 60
The question clearly states that Rohit is more efficient than Virat. Therefore, Rohit will take lesser time than Virat.
So Rohit will take 30 days

Correct Option: 6 Best Solution (0)

07 Oct 2020 Handshakes

In a party there are 123 persons present. If each of them shakes hand with all the other persons,in total how many handshakes will take place?

OPtion

1) 7503
2) 7513
3) 7523
4) 7533
5) 7543
6) 7553
7) 7563
8) 7573
9) 7583
10) None of these

Solution

Out of 123 persons, the first person will shake hand with 122 persons.
The second person will shake hand with 121 persons (because he has already shaken hand with first person).
The third person will shake hand with 120 persons and so on. The second last person shakes hand with only one person. And last will shake hand with none
(because he has already shaken hand with all persons).
In order to find the total number of handshakes you have to add all the natural numbers from 1 to 122 i.e. ∑ 122.
∑122 = 123 x 122/2 = = 7503 handshakes.

Correct Option: 1 Best Solution (2)

06 Oct 2020 Profit and Loss

The profit earned by selling a chocolate for Rs 900 is double the loss incurred when the same chocolate is sold for Rs.490. At what price should the chocolate be sold to make 25% profit?

OPtion

1) 720
2) 750
3) 700
4) 775
5) 780
6) 790
7) 800
8) 820
9) 725
10) None of these

Solution

Let C.P be Rs. x

900 - x = 2(x - 490) => x = Rs.626.67



C.P = 626.67 gain required is 25%

S.P = [(100+25) x 626.67] / 100 = Rs.783.33

Correct Option: 10 Best Solution (0)

05 Oct 2020 Average

The average of runs scored by Afridi of 10 innings was 32. How many runs must he make in his next innings so as to increase his average of runs by 4 ?

OPtion

1) 71
2) 69
3) 73
4) 67
5) 75
6) 76
7) 66
8) 65
9) 64
10) None of these

Solution

Average = total runs / no.of innings = 32

So, total = Average x no.of innings = 32 x 10 = 320.



Now increase in avg = 4runs. So, new avg = 32+4 = 36runs

Total runs = new avg x new no. of innings = 36 x 11 = 396

Runs made in the 11th inning = 396 - 320 = 76

Correct Option: 6 Best Solution (1)

02 Oct 2020 RANK of the word

Rank of the word GANDHI in the dictionary of words formed by the letters of the word GANDHI?

OPtion

1) 209
2) 249
3) 258
4) 257
5) 255
6) 259
7) 253
8) 251
9) 250
10) None of these

Solution

240 + 0 + 18 + 0 + 0 + 0 = 258
258 + 1 = 259
i.e., Rank of the word 'GANDHI' = 259

Correct Option: 6 Best Solution (3)