M4maths Previous Puzzles

06 Dec 2017 Probability

What is the probability of getting a product of 36 from three throws of a dice?

OPtion

1) 9/216
2) 6/216
3) 1/24
4) 1/27
5) 15/216
6) 2/27
7) 11/216
8) 10/216
9) 2/36
10)None of these

Solution

Total Number of possible outcomes = 6C1*6C1*6C1 = 6*6*6 = 216
Positive outcomes must satisfy D1*D2*D3= 36
Below are such values of D1, D2 and D3:
1, 6, 6
2, 6, 3
2, 3, 6
3, 6, 2
3, 4, 3
3, 3, 4
3, 2, 6
4, 3, 3
6, 6, 1
6, 3, 2
6, 2, 3
6, 1, 6


Count of positive outcome = 12
Probability = Positive outcome/Total Possible Outcomes = 12/216 = 1/18 = 2/36
Option 9)

Correct Option: 9 Best Solution (7)

05 Dec 2017 Ratio

Jo Jo's collection contains US, Indian and British coins. If the ratio of US to Indian coins is 9 to 5 and the ratio of Indian to British coins is 8 to 3, what is the ratio of US to British coins?

OPtion

1) 1:3
2) 9:8
3) 64:40
4) 64:48
5) 75:45
6) 25:9
7) 24:5
8) 5:1
9) 72:25
10) None of these

Solution

Ratio of US to Indian coins is 9:5
U/I = 9:5
= 72:40

ratio of Indian to British coins is 8 : 3
I/B = 8:3
=40:15

Now , Ratio of US to British coins
U/B = 72:15 = 24:5

Correct Option: 7 Best Solution (5)

04 Dec 2017 Profit and Loss

A vendor bought 390 chocolates for 3120 rupees. How many chocolates in 3120 rupees must he sell to gain 50%?

OPtion

1) 256
2) 296
3) 275
4) 260
5) 236
6) 300
7) 306
8) 290
9) 285
10)None of these

Solution

CP of 1 Chocolate = 3120/390 = Rs. 8
SP of 1 Chocolate for 50% profit = 8*1.5 = Rs. 12
So in 3120 Rupess how many chocolates should be sold = 3120/12 = 260

Option 4)

Correct Option: 4 Best Solution (17)

01 Dec 2017 Trains

Two trains are running in same directions on parallel tracks. Train running with speed 64 Km/hr has 270 meter length and the second train running with speed of 36km/hr has 330 meter length.
What is the time taken by the faster train to pass through the complete length of slower train (from front to rear)?

OPtion

1) 77.50 seconds
2) 78.9 seconds
3) 79.8 seconds
4) 79.0 seconds
5) 70.8 seconds
6) 76.5 seconds
7) 76.8 seconds
8) 77.14 seconds
9) 79.08 seconds
10) None of these

Solution

Relative speed= 64-36 = 28 km/hr = 28 * 5/18 = 70/9 m/sec

We are calculating the time taken by the faster train to completely pass the lenght of slower one.
Hence, distance = length of the slower train + lenght of faster train = 270+330 = 600 metre

Time = 600/70/9 = 77.14 seconds

Option 8)

Correct Option: 8 Best Solution (0)

30 Nov 2017 ODD Number

How many factors of 1247465610 are odd numbers?

OPtion

1) 24
2) 36
3) 120
4) 60
5) 48
6) 75
7) 180
8) 16
9) 90
10) None of these

Solution

1247465610 = 73^2 * 17^2 * 5^1 * 3^4 * 2^1

Any factor of this number should be of the form 73^a * 17^b * 5^c * 3^d * 2^e

For the factors of this number to be an odd number e should be 0

a can take values 0, 1, 2
b can take values 0, 1, 2
c can take values 0, 1
d can take values 0, 1, 2, 3, 4
and e can take values 0


Total number of odd factors = 3*3*2*5= 90

Option 9)

Correct Option: 9 Best Solution (6)

29 Nov 2017 Mean, Median, & Mode

Find the product of mean, median and mode (i.e. you need to find mean*median*mode)for the following list of values?
41; 13; 13; 27; 28; 31; 27; 17; 34; 28; 27

OPtion

1) 17775
2) 18225
3) 18025
4) 18954
5) 18075
6) 17075
7) 17725
8) 9477
9) 17825
10) None of these

Solution

Mean = Sum of nos. / Count of numbers = 286/11 = 26
Median = Middle term when number are arranged in ascending order = 27
Mode = Number which is present maximum number of times =27
Product = 26*27*27 = 18954

Option 4)

Correct Option: 4 Best Solution (2)

28 Nov 2017 Speed and Time

A boatman goes 11 km against the current of the stream in 2 hour and goes 16.5 kms along the current in 60 minutes. How long will it take to go 41.25 km in stationary water?

OPtion

1) 3 hours 33 minutes
2) 3 hours 75 minutes
3) 3.45 hours
4) 3.30 hours
5) 3 hours 45 minutes
6) 3.03 hours
7) 3 hours 20 minutes
8) 3 hours 25 minutes
9) 3.25 hours
10)None of these

Solution

Speed (upstream) =11/2 = 5.5 km/hr
Speed (downstream)= 16.5/1= 16.5 km/hr

Speed in still water = 1/2 (5.5+16.5) = 11 km/hr

Time taken in stationary water to go 41.25 KM = 41.25/11 = 3.75 hr = 3 hours 45 minutes

Option 2)

Correct Option: 5 Best Solution (0)

27 Nov 2017 Profit and Loss

Beeru buys an old bike for Rs. 29375 and spends Rs. 4150 on its repairs. If he sells the bike for Rs. 39500, his gain percent is:

OPtion

1) 17.02 %
2) 17.82 %
3) 17.09 %
4) 17.05 %
5) 17.92 %
6) 17.62 %
7) 17.08 %
8) 17.30 %
9) 17.52 %
10) None of these

Solution

Cost Price (C.P.) = Rs. ( 29375 + 4150) = Rs. 33525

Selling Price (S.P.) = Rs. 39500

Gain = (S.P.) - (C.P.) = Rs.(39500 - 33525) = Rs. 5975

Gain % = (5975/33525)*100 = 17.82252 = ~17.82 %

Option 2)

Correct Option: 2 Best Solution (2)

24 Nov 2017 CI & SI

The difference between simple interest and the compound interest on a certain amount of money for 3 years at 7.0% per annum is Rs. 192.55. The sum is:

OPtion

1) Rs.12600
2) Rs.12080
3) Rs.12800
4) Rs.18280
5) Rs.12008
6) Rs.12500
7) Rs.12900
8) Rs.12700
9) Rs.12750
10)None of these

Solution

Let the sum be Rs.x. then S.I.=(x*7*3 / 100) = 21x/100 = 0.21x
C.I = [x(1+7/100)^3 -x] = [x(107/100)^3 -x] = 0.225043x
CI-SI=192.55
=> 0.225043x- 0.210x = 192.55
=> 0.015043x = 192.55
=> x = 12800

Option 3)

Correct Option: 3 Best Solution (0)

23 Nov 2017 Simplifcation

There are two buildings P and Q. If 25 persons are sent from P to Q, then the number of persons in each building is the same. If 55 persons are sent from Q to P, then the number of persons in P is double the number of persons in Q. How many persons are there in building P?

OPtion

1) 210
2) 220
3) 225
4) 190
5) 235
6) 215
7) 240
8) 265
9) 250
10) None of these

Solution

Let number of persons in building P be P and
number of persons in building Q be Q

P-25 = Q+25
=> P = Q + 50 ---- (i)

P+55= 2(Q-55)
=> P + 165 = 2Q ---- (ii)

Putting value of P from (i) in (ii)
Q+ 50 + 165 = 2Q
Q = 215
P = 265

Correct Option: 8 Best Solution (0)