M4maths Previous Puzzles

02 Aug 2017 Discount

The marked price of a dress is Rs.6000. A shopkeeper offers 30% discount on this shirt and then again offers 15% discount on the new price, and then and then again offers 10% discount on the new price . How much will you have to pay, finally?

OPtion

1) 3213
2) 3200
3) 3123
4) 3223
5) 3312
6) 3321
7) 3231
8) 3333
9) 3431
10) None of these

Solution

Price after 1st Discount = 6000*70/100 = 4200
Price after 2nd Discount = 4200*85/100 = 3570
Price after 3rd discount = 3570*90/100 = 3213

Hence Option 1)

Correct Option: 1 Best Solution (13)

01 Aug 2017 Mixture

A merchant has 999 kg of sugar, part of which he sells at 12% loss and the rest at 15% profit. He gains 7% on the whole. What is the difference between the quantities of sugar sold at 15% profit and that sold at 12% loss?

OPtion

1) 296 kg
2) 395 kg
3) 407 kg
4) 705 kg
5) 703 kg
6) 401 kg
7) 449 kg
8) 409 kg
9) 411 kg
10)None of these

Solution

(Quantity of Cheaper)/(Quantity of Dearer) = (Price of Dearer - Mean Price)/(Mean Price - Price of Cheaper)

(Quantity of Cheaper)/(Quantity of Dearer) = (115 - 107)/(107-88) = 8/19

Total Quantity = 999 KG

The quantity sold at 12% loss is = (8/27) * 999 = 296 Kgs
The quantity sold at 15% profit is = (19/27) * 999 = 703 Kgs
Diff between quantities = 703-296 = 407 KGs

Option 3)

Correct Option: 3 Best Solution (14)

31 Jul 2017 Probability

A number is randomly picked from following list 2, 3, 4, 5, 6, 7, 8, 9.... and so on till 29.
What is the probability that its a prime number?

OPtion

1) 10/27
2) 10/29
3) 5/13
4) 9/28
5) 5/28
6) 5/14
7) 7/16
8) 9/29
9) 8/28
10) None of these

Solution

Count of total number betweeen 2 to 29 = 28

List of Prime numbers between 2 to 29 (both inclusive):
2, 3, 5, 7, 11, 13, 17, 19, 23, 29
Count of (2, 3, 5, 7, 11, 13, 17, 19, 23, 29) = 10

Probability of selecting prime number from numbers between 2 to 29 = 10/28 = 5/14

Correct Option: 6 Best Solution (13)

28 Jul 2017 Stocks and Share

A man invested Rs. 4320 in Rs. 10 shares quoted at Rs. 9. If the rate of dividend be 13%, his annual income is:

OPtion

1) Rs. 299.1
2) Rs. 600
3) Rs. 674
4) Rs. 62.4
5) Rs. 620
6) Rs. 664
7) Rs. 310
8) Rs. 324
9) Rs. 320
10) None of these

Solution

Number of shares = (4320/9) = 480

Face value = 480*10 = 4800

Annual Income = (13/100)*4800 = 624

Option 10

Correct Option: 10 Best Solution (13)

27 Jul 2017 Standard Deviation

Ricky scored below runs in his last 7 innings
2 runs, 19 runs, 38 runs, 9 runs, 13 runs, 87 runs, 49 runs
Find population standard deviation for his score in last 7 innings?

OPtion

1) 27.72
2) 27.32
3) 27.22
4) 27.12
5) 27.52
6) 27.42
7) 27.82
8) 27.62
9) 27.92
10)None of these

Solution

Mean of 7 score = (2+9+38+19+13+87+49)/7 = 217 =31
Sum of squared difference from mean for each number = (31-2)^2 + (31-9)^2 + (31-38)^2 + (31-19)^2 + (31-13)^2 + (31-87)^2 + (31-49)^2
= 7379

Average of Squared difference (Variance) = 7379/7 = 757.43
Population Standard Deviation = Square root of variance = 757.43^1/2 = 27.52

Correct Option: 5 Best Solution (13)

26 Jul 2017 Coding-Decoding

If
397 is coded as 210191,
459 is coded as 360881 and
123 is coded as 030260

Then what is the code for 789?

OPtion

1) 631822
2) 630742
3) 631824
4) 630824
5) 630942
6) 660842
7) 638842
8) 630822
9) 631042
10) None of these

Solution

Lets denote original number as abc
The coded number could be broken into 3 part of 2 digits each
First two digits of coded number from left is derived as = a*c =7*9 = 63
Middle two digits are derived as = a+c-b = 7+9-8 = 08
Last two digits are derived as = Reverse of (a+b+c) = Reverse of(7+8+9) = Reverse of (24) = 42

Hence 630842
Option 10)

Correct Option: 10 Best Solution (29)

25 Jul 2017 Probability

There are 8 boys and 5 girls in a class. If three students are selected at random, what is the probability that 2 girls and 1 boy are selected?

OPtion

1) 3/21
2) 7/36
3) 1/4
4) 7/23
5) 80/285
6) 40/286
7) 8/286
8) 13/40
9) 40/143
10) None of these

Solution

Total number of ways of selecting 3 students = 13C3
Total number of selecting 1 boy = 8C1
Total number of selecting 2 Girl = 5C2

Probability = (8C1 * 5C2)/13C3 = (8*5*4/2)/(13*12*11/3*2)
=> 80/286 = 40/143

Correct Option: 9 Best Solution (25)

24 Jul 2017 Profit and Loss

When an item is sold for Rs. 17,600, the owner loses 12.0%. At what price should that plot be sold to get a gain of 12.50 % ?

OPtion

1) 18600
2) 19400
3) 22500
4) 19600
5) 20000
6) 21600
7) 20000
8) 23400
9) 24400
10) None of these

Solution

When the item is sold for Rs. 17,600, loss is 12%
So cost price = 17600 * 100/88 = 20,000

To gain 12.5% selling price = 112.5*20,000/100 = 22,500

Correct Option: 3 Best Solution (35)

21 Jul 2017 Age

Mohita's mother was 21 years of age when she was born while her father was 38 years old when her brother ten years younger to her was born. What is the difference between the ages of her parents?

OPtion

1) 7.5 Year
2) 8.5 Years
3) 11 Years
4) 12 Years
5) 6 Years
6) 10 Years
7) 9 Years
8) 8 Years
9) 7 Years
10)None of these

Solution

Age of Mohita's mother when Mohita was born = 21
Age of Mohita's father when Mohita was born = 38−10 =28
Required difference of age =28−21= 7 Years

Option 9)

Correct Option: 9 Best Solution (44)

20 Jul 2017 Time and Work

P can do a work in 19 days. Q can do the same work in 9.5 days and R can do the same in 28.5 days. Q and R start the work and leave after 3 days. P finishes the remaining work in X days. What is the value of X?

OPtion

1) 10.5 days
2) 9.5 days
3) 11.0 days
4) 12.0 days
5) 12.5 days
6) 10.0 days
7) 11.5 days
8) 13.0 days
9) 9.0 days
10) None of these

Solution

Amount of work done by Q and R in 3 days = 3*(1/9.5 + 1/28.5) = 3*4/28.5 = 3*8/57 = 8/19
Amount of work remaining after 3 days = 11/19

Amount of work done by P in 1 day = 1/19
So for 1/19 work P takes 1 day
Hence for 11/19 work P would take (1/(1/19))*11/19 = 11 days

Correct Option: 3 Best Solution (11)