M4maths Previous Puzzles

27 Aug 2020 True Discount

The true discount on Rs. 1469 due 4 months hence is Rs. 113. The rate percent is?

OPtion

1) 25
2) 19
3) 13
4) 15
5) 18
6) 30
7) 10
8) 21
9) 24
10) None of these

Solution

Present Worth = 1469-113 =Rs. 1356

Rate = [100 x 113] / [1356 x (1/3)] =25%

Correct Option: 1 Best Solution (4)

26 Aug 2020 Area

A tank is 25m long 12m wide and 6m deep. The cost of plastering its walls and bottom at 225 paise per sq m is

OPtion

1) 558
2) 668
3) 568
4) 666
5) 888
6) 999
7) 1180
8) 1674
9) 750
10) None of these

Solution

Area to be plastered = [2(l+b)×h]+(l×b)

=[2(25+12)×6]+(25×12)=744sq.m

Cost of plastering = 744×225100=Rs.1674

Correct Option: 8 Best Solution (6)

25 Aug 2020 Marks

In JEECAT exam, a student scores four marks for every correct answer and loses one mark for every wrong answer. If Jaggu attempts all sixty questions and secures 130 marks, the no of questions Jaggu attempted correctly is :

OPtion

1) 44
2) 25
3) 46
4) 39
5) 36
6) 38
7) 45
8) 40
9) 43
10) None of these

Solution

Let the number of correct answers be X.

Number of incorrect answers = (60 – X).

4x – (60 – x) = 130

=> 5x = 190

=> x = 38

Correct Option: 6 Best Solution (11)

24 Aug 2020 Percentage

The price of a diamond is decreased from Rupees one crore to Rupees eighty five lakhs. Find the percentage of decrease.

OPtion

1) 14.29
2) 16.67
3) 25.00
4) 20.00
5) 12.50
6) 10.00
7) 15.00
8) 24.00
9) 19.00
10) None of these

Solution

10000000 - 8500000 = 1500000
% = 1500000*100/10000000 = 15%

Correct Option: 7 Best Solution (9)

21 Aug 2020 Handshakes

In a party there are 49 persons present. If each of them shakes hand with all the other persons,in total how many handshakes will take place?

OPtion

1) 1116
2) 1126
3) 1136
4) 1146
5) 1156
6) 1166
7) 1170
8) 1176
9) 1196
10) None of these

Solution

Out of 49 persons, the first person will shake hand with 48 persons.
The second person will shake hand with 47 persons (because he has already shaken hand with first person).
The third person will shake hand with 46 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 48 i.e. ∑ 48.
∑48 = 48 x 49/2 = = 1176 handshakes.

Correct Option: 8 Best Solution (5)

20 Aug 2020 Number

A = (126a^2 + 113a + 11)/a; where A belongs to integer. How many integral solutions of A are possible?

OPtion

1) 2
2) 3
3) 6
4) 9
5) 8
6) 7
7) 10
8) 12
9) 4
10) None of these

Solution

(126a^2 + 133a +11)/a = 126a + 133 + 11/a

Now we can see that whatever the value of ‘a’, 126a + 133 will always give an integral value.
So, it now depends upon 11/a only

=> a can have any integral value, which is a factor of 11.
The integers, which will satisfy this condition are ±1, ±11. Thus, in total,a can take 4 values.

Correct Option: 9 Best Solution (0)

19 Aug 2020 Mensuration

A rope is 89 cm long. It is cut into 3 pieces. The longest piece is 3 times as long as the middle-sized piece &

the shortest piece is 44 cm shorter than the longest piece. Find the length of the shortest piece (in cm).

OPtion

1) 12
2) 19
3) 13
4) 9
5) 18
6) 15
7) 10
8) 21
9) 4
10) None of these

Solution

Let the middle be x CM

Longest piece = 3x cm
Smallest piece = 3x - 44

x+3x+3x-44 = 89
7x = 133
x= 19
shortest piece = 3*19-44 = 13 cm

Correct Option: 3 Best Solution (5)

18 Aug 2020 Numbers

The product of two numbers is 39375 and the quotient, when the larger one is divided by the smaller, is 7. The sum of the numbers is :

OPtion

1) 800
2) 500
3) 600
4) 840
5) 640
6) 540
7) 480
8) 700
9) 750
10) None of these

Solution

Let the numbers be x and y.
Then, xy = 39375 and x/y = 7.
(xyxy//)=39375/7
=>y2 =5625
=> y = 75
=> x = 7y = 7 x 75 = 525.
Sum of the numbers = 525 + 75 = 600.

Correct Option: 3 Best Solution (6)

17 Aug 2020 Numbers

Three numbers are in the ratio 3 : 6 : 9 and their average is 66. The largest number is :

OPtion

1) 72
2) 81
3) 90
4) 99
5) 60
6) 66
7) 100
8) 110
9) 144
10) None of these

Solution

Let the numbers be 3x, 6x and 9x, Then, (3x + 6x + 9x ) / 3 = 66

=> 6x = 66

=> x = 11.

Largest = 11x = 11*9 = 99

Correct Option: 4 Best Solution (4)

14 Aug 2020 Permutation

A five-digit number is formed using digits 1, 3, 5, 8 and 9 without repeating any one of them. What is the sum of all such possible numbers?

OPtion

1) 6666600
2) 6666680
3) 6606600
4) 6066600
5) 6931264
6) 6933264
7) 6932264
8) 6934264
9) 6935264
10) None of these

Solution

If we fix 1 at the unit’s place, the other digits can be arranged in 4! = 24 ways.

So, there are 24 numbers which have 1 at the unit’s place and sum of these numbers is 24.

Similarly, there will be 24 numbers each with 3, 5, 8 and 9 at the unit’s place.

So, the sum of all the numbers at the unit’s place will be:

24 + 24 × 3 + 24 × 5 + 24 × 8 + 24 × 9 = 624

Similarly, the sum of the digits at the ten’s place, hundred’s place,

thousand’s place and ten thousand’s place will be 624.

So, the sum of all numbers = 624 (1 + 10 +100 +1,000 +10,000) = 6933264

Correct Option: 6 Best Solution (5)