M4maths Previous Puzzles

12 May 2021 Height

The height of Aman is 6.6 feet and that of Raman is 162.00 cm. Difference of their heights in inches is (approximate value)?

OPtion

(1) 15.42
(2) 12.00
(3) 14.80
(4) 14.50
(5) 16.00
(6) 15.00
(7) 16.50
(8) 10.00
(9) 13.00
(10) None of the above

Solution

Height of Aman in Inches = 6.6 x 12 = 79.2 inch
Height of Raman in inches = 162/2.54 = 63.7795
So, the difference in their heights will be = 79.2 – 63.7795 = 15.4205 inch.

Correct Option: 1 Best Solution (3)

11 May 2021 PROBABILITY

A bag contains 6 black and 8 red balls. A ball is drawn at random from the bag. If the ball drawn is black, a coin is tossed twice otherwise no coin is tossed. What is the probability to get two heads respectively on the coins?

OPtion

1) 1/8
2) 1/4
3) 3/7
4) 1/7
5) 3/28
6) 3/14
7) 2/7
8) 1/2
9) 1/3
10) None of the above

Solution

Probability of drawing a black ball is 6/14 = 3/7
After then the probability of getting two successive heads is 1/2 * 1/2 = 1/4
Net probability = 3/7 * 1/4 = 3/28

Correct Option: 5 Best Solution (0)

10 May 2021 Marks

A student gets 4 marks for each correct answer and 1 mark is deducted for a wrong answer. If he had done 80 questions at all and he has got only 240 marks, The correct answer he has attempted are?

OPtion

1) 62
2) 68
3) 72
4) 74
5) 58
6) 60
7) 64
8) 55
9) 53
10) None of the above

Solution

Suppose he has done x questions correctly.
Then it means he has done (80-x) questions wrong.
So, 4 (x) – 1 (80 -x ) =240
5x – 80 = 240
5x = 320
X = 64

Correct Option: 7 Best Solution (3)

07 May 2021 Surface Area

Find the surface area of a cuboid 16 m long, 14 m broad and 17 m high (in m^2)

OPtion

1) 864
2) 868
3) 872
4) 786
5) 687
6) 1468
7) 1486
8) 1406
9) 1496
10) None of these

Solution

Surface area = [2 (16 x 14 + 14 x 17 + 16 x 17)] sq.m
= (2 x 434)sq.m = 1468

Correct Option: 6 Best Solution (2)

06 May 2021 PROBABILITY

In a bag there are 10 red and 15 blue marbles. Two marbles are drawn in succession without replacement. What is the probability that first is red and second is blue

OPtion

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

Solution

Probability that first one is red = 10/25 = 2/5
Probability that second one is blue = 15/24 = 5/8
probability that first is red and second is blue = 2/5 * 5/8 = 1/4

Correct Option: 5 Best Solution (3)

05 May 2021 Speed of stream

The speed of the motor boat in still water is 25/3 m/s. It goes 75 km downstream and comes back in 9 hours. Find the speed of the current in km/hr

OPtion

1) 50/9
2) 25
3) 13
4) 13.33
5) 20
6) 15
7) 18
8) 14
9) 12
10) None of these

Solution

Let the speed of the current = 'x' km/hr
Speed of motor boat = 25/3 m/s = (25/3)*18/5 = 30 KM/hr
We have 75/(30+x) + 75/(30-x) = 9
⇒ 75(60/(900-x2)) = 9
⇒ 900-x2 = 500
⇒ x2 = 400
⇒ x = 20km/hr

Correct Option: 5 Best Solution (0)

04 May 2021 Discount

The true discount on Rs. 1452 due 4 months hence is Rs. 132. The rate percent is?

OPtion

1) 12
2) 19
3) 13
4) 15
5) 18
6) 30
7) 10
8) 21
9) 24
10) None of these

Solution

Present Worth = 1452-132 =Rs. 1320
Rate = [100 x 132] / [1320 x (1/3)] =30%

Correct Option: 6 Best Solution (3)

03 May 2021 Marks

Lokesh got 98 % marks. Avinash got 1 % marks less than Lokesh. How much more % marks Lokesh got w. r. t. marks of Avinash.

OPtion

1) 1.431
2) 1.031
3) 1.231
4) 1.098
5) 2.444
6) 2.076
7) 2.098
8) 2.043
9) 3.111
10) none of these

Solution

Marks of Lokesh = 98 %
so that of Avinash will be 98-1 = 97%
now we have to find the % of difference of marks w. r. t. marks of Avinash it will be
1*100/97 = 100/97 = 1.031

Correct Option: 2 Best Solution (2)

30 Apr 2021 arrangement

How many ways are possible to arrange 4 boys and 3 girls for a dinner, if there are two straight benches of capacity 5 and 2 persons for their sitting?

OPtion

1) 720
2) 5040
3) 2520
4) 840
5) 4320
6) 2460
7) 2860
8) 120
9) 24
10) None of the above

Solution

Total no. of persons = 7
Since benches are straight, therefore arranging them in benches of capacity 5 and 2 persons is
equivalent to arranging them in a straight bench of capacity 7 persons.
Total no. of methods
= 7*6*5*4*3*2*1 = 5040

Correct Option: 2 Best Solution (1)

29 Apr 2021 Population

Total population of a city is 10 lacs. If it increases by 10 % every year than after 3 year it will be?

OPtion

1) 15 lacs 41 thousand
2) 13 lacs
3) 13 lacs 21 thousand
4) 12 lacs 31 thousand
5) 16 lacs 21 thousand
6) 16 lacs 31 thousand
7) 12 lacs 21 thousand
8) 13 lacs 31 thousand
9) 12 lacs 41 thousand
10) None of the above

Solution

Population after 3 years = 10 lacs * 1.1 * 1.1 * 1.1
= 13.31 lacs

Correct Option: 8 Best Solution (3)