M4maths Previous Puzzles

22 Nov 2017 Simple Interest

Divide Rs. 7930 into 3 parts so that their amount after 2,3 and 4 years respectively may be equal, the rate of interest being 5% per annum at simple interest. The first part is

OPtion

1) 2640
2) 2530
3) 2760
4) 2630
5) 2520
6) 2780
7) 2650
8) 2540
9) 2750
10) None of these

Solution

Let the parts be x, y and z
x + (x * 2 * 5/100) = y + (y * 3 * 5/100) = z + (z * 4 * 5/100)
11x/10 = 23y/20 = 6z/5 = k
x = 10k/11, y = 20k/23, z = 5k/6
But x + y + z = 7930
10k/11 + 20k/23 + 5k/6 = 7930
k = 3036
x = (10/11)*3036 = 2760
Hence, the first part is Rs. 2760

Correct Option: 3 Best Solution (0)

21 Nov 2017 Age

A is 7 years older than B who is four times as old as C. The total of the ages of A, B and C is 97 years. What is the product of B and A ages?

OPtion

1) 2660 years
2) 1880 years
3) 470 years
4) 400 years
5) 1860 years
6) 2680 years
7) 1780 years
8) 1740 years
9) 2440 years
10)None of these

Solution

Let’s assume Age of B be B years
Age of A = B+7
Age of C = B/4

Total age = B + 7 + B + B/4 = 97
Solving 9B/4 = 90
B = 40
A = B+7 = 40+7 = 47
C = 40/4 = 10

B*A = 1880

Option 2)

Correct Option: 2 Best Solution (0)

20 Nov 2017 Profit and Loss

A vendor bought 37 chocolates for 185 rupees. How many chocolates in 185 rupees must he sell to gain 50%?

OPtion

1) 60
2) 65
3) 66
4) 50
5) 55
6) 54
7) 56
8) 58
9) 62
10)None of these

Solution

CP of 1 Chocolate = 185/37 = Rs. 5
SP of 1 Chocolate for 50% profit = 20*1.5 = Rs. 7.5
So in 185 Rupess how many chocolates should be sold = 185/7.5 = 24.66

Option 10)

Correct Option: 10 Best Solution (0)

17 Nov 2017 Discount

The marked price of a mobile phone is Rs.12000. A shopkeeper offers three successive discount of 15% each. How much will you have to pay, finally?

OPtion

1) 7339.5
2) 7349.5
3) 7319.5
4) 7389.5
5) 7359.5
6) 7379.5
7) 7309.5
8) 7399.5
9) 7369.5
10) None of these

Solution

Price after 1st Discount = 12000*85/100 = 10200
Price after 2nd Discount = 10200*85/100 = 8670
Price after 3rd discount = 8670*85/100 = 7369.5

Hence Option 9)

Correct Option: 9 Best Solution (0)

16 Nov 2017 Percentage

In a shop, the profit is 160% of the cost. If the cost increases by 20% but the selling price remains constant, find out approximately what percentage of the selling price is the profit?

OPtion

1) 153.85
2) 152.75
3) 154.5
4) 151.65
5) 53.85
6) 52.75
7) 54.5
8) 116.66
9) 50.35
10) None of these

Solution

Let the CP be Rs. 100
SP considering 160% of profit = 100+160 = Rs. 260
CP after 20 increase = Rs. 120

Profit = 260 – 120 = Rs. 140
Profit % on SP = (140/260)*100 = 53.85 (approximately)
Option 5)

Correct Option: 5 Best Solution (0)

15 Nov 2017 Speed and Distance

Ramachandran could either walk or drive to office. The time taken to walk to the office is 13 times the driving time. One day, his wife took the car making him walk to office. After walking 2 km, he reached a temple when his wife called to say that he can now take the car. Ramanujam figured that continuing to walk to the office will take as long as walking back home and then driving to the office. Calculate the distance between the temple and the office in KMs.

OPtion

1) 13/3
2) 8/3
3) 7/3
4) 5/2
5) 2.0
6) 2.5
7) 6/2
8) 3.5
9) 3.25
10)None of these

Solution

Suppose the distance between his home and office is x km. Then, distance between his office and temple is (x – 2) km.
If he walks at a speed of y km/hr. Then his driving speed = 13y km/hour, as he is 13 times faster in car.

Then,
2/y + x/13y = (x – 2)/y
Or, 2 + x/13 = x – 2
or 12x/13 = 4
Or, x = 13/3
Finally, x – 2 = 13/3-2 = 7/3
Option 3)

Correct Option: 3 Best Solution (0)

14 Nov 2017 Trains

Two trains are running in opposite directions on parallel tracks. Train running with speed 64 Km/hr has 270 meter length and the second training running with speed of 36km/hr has 330 meter length.
What is the time taken by the faster train to pass the driver of the slower one?

OPtion

1) 9.72 seconds
2) 9.14 seconds
3) 9.8 seconds
4) 9.0 seconds
5) 9.82 seconds
6) 9.52 seconds
7) 9.9 seconds
8) 9.6 seconds
9) 9.5 seconds
10) None of these

Solution

Relative speed= 64+36 = 100 km/hr = 100 * 5/18 = 250/9 m/sec

We are calculating the time taken by the faster train to completely pass the driver of slower train.
Hence, distance = lenght of faster train = 270 metre

Time = 270/250/9 = 9.72 seconds

Option 1)

Correct Option: 1 Best Solution (5)

13 Nov 2017 Simple Interest

At what rate of simple interest a sum of Rs. 2017 would amount to Rs. 4034 in 8 years?

OPtion

1) 10 %
2) 10.5 %
3) 11 %
4) 11.5 %
5) 12 %
6) 12.75 %
7) 13 %
8) 12.5 %
9) 14 %
10)None of these

Solution

SI = PRT/100
4034 - 2017 = 2017*R*8/100
=> R = 2017 * 100/ (2017*8)
=> R = 12.5
Option 8)

Correct Option: 8 Best Solution (7)

10 Nov 2017 Probability

What is the probability of getting a product of 12 from three throws of a dice?

OPtion

1) 12/216
2) 13/216
3) 14/216
4) 15/226
5) 16/236
6) 1/19
7) 5/72
8) 1/18
9) 16/216
10)None of these

Solution

Total Number of possible outcomes = 6C1*6C1*6C1 = 6*6*6 = 216
Positive outcomes must satisfy D1*D2*D3= 12
Below are such values of D1, D2 and D3:
1, 6, 2
1, 4, 3
1, 3, 4
1, 2, 6
2, 6, 1
2, 3, 2
2, 2, 3
2, 1, 6
3, 4, 1
3, 2, 2
3, 1, 4
4, 3, 1
4, 1, 3
6, 2, 1
6, 1, 2

Count of positive outcome = 15
Probability = Positive outcome/Total Possible Outcomes = 15/216 = 5/72
Option 7)

Correct Option: 7 Best Solution (2)

09 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?
27; 11; 11; 28; 58; 31; 27; 58; 35; 28; 27

OPtion

1) 20436
2) 21436
3) 22436
4) 23456
5) 24436
6) 25436
7) 27436
8) 28436
9) 29436
10) None of these

Solution

Mean = Sum of nos. / Count of numbers = 341/11 = 31
Median = Middle term when number are arranged in ascending order = 28
Mode = Number which is present maximum number of times =27
Product = 31*28*27 = 23436

Option 10)

Correct Option: 10 Best Solution (0)