M4maths Previous Puzzles

21 Oct 2021 Study

In a college, 25% of the student’s study Hindi and English. 45% of the student’s study English. What is the probability of a student studying Hindi given he/she is already studying English?

OPtion

1. 0.675
2. 0.580
3. 0.875
4. 0.725
5. 0.555
6. 0.445
7. 0.465
8. 0.665
9. 0.659
10. None of the above

Solution

P(T and E) = 0.25
P(E) = 0.45
P(T/E) = P(T and E)/P(E) = 0.25/0.45
= 0.555

Correct Option: 5 Best Solution (2)

20 Oct 2021 arrangement

There are 8 A-type, 2 B-Type and 4 C-type objects are in a bag. All the 14 objects are drawn one by one and arranged in a row. Find out the number of different arrangements possible.

OPtion

1. 40240
2. 50250
3. 50050
4. 55055
5. 62025
6. 66046
7. 45045
8. 48056
9. 42016
10. None of the above

Solution

Number of different arrangements possible = {14!} / {8! 2! 4!}
= {14×13×12×11×10×9×8×7×6×5×4×3×2 } / {(8×7×6×5×4×3×2 ) (2) (4×3×2)}}
= {14×13×12×11x10x9} / {(2)(4×3×2)} = {7×13×3×11x5×3} = 45045

Correct Option: 7 Best Solution (4)

18 Oct 2021 share

The cost of a share is decreased by 20%. If the original cost is $120, find the decrease cost.

OPtion

1. 110
2. 100
3. 102
4. 104
5. 98
6. 95
7. 96
8. 108
9. 90
10. None of the above

Solution

Original cost = $120
Decrease in it = 20% of $120 = 20/100 × 120
= 2400/100 = $24
Therefore, decrease cost = $120 - $24 = $96

Correct Option: 7 Best Solution (2)

15 Oct 2021 Rectangle

The length of a rectangle doormat is twice its breadth. If its length is decreased by 15cm and breadth is increased by 15 cm, the area of the rectangle is increased by 275sq. cm. Find the length of the rectangle.

OPtion

1. 33.33
2. 80
3. 40
4. 60.50
5. 66.66
6. 65.30
7. 60
8. 50.50
9. 55.55
10. None of the above

Solution

Let breadth = x.
Then, length = 2x
Then, (2x -15) (x + 15) - 2x * x = 275
30x – 15x- 225= 275
15x = 500
x = 33.33
Length of the rectangle = 2x = 66.66 cm.

Correct Option: 5 Best Solution (2)

14 Oct 2021 Tax

Ramesh went to a shop and bought a book worth Rs. 105, out of which 72 Paise went on sales tax on taxable purchases. If the tax rate was 18%, then what was the cost of the tax free Book ?

OPtion

1. 102.20
2. 101.50
3. 99.58
4. 99.01
5. 99.1
6. 102.28
7. 100.28
8. 98.28
9. 99.28
10. None of the above

Solution

Total cost of the items he purchased = Rs.105
Given that out of this Rs.105, 72 Paise is given as tax
=> Total tax incurred = 90 Paise = Rs.72/100
Let the cost of the tax free items = x
Given that tax rate = 18%
∴ (105− 72/100 − x)18/100 = 72/100
⇒ 18(105 −0.72 −x) = 72
⇒ (105 − 0.72 − x) = 72
x = 105 − 0.72 – 4
X= 100.28

Correct Option: 7 Best Solution (1)

13 Oct 2021 Exam

In final exam of class 10th there are 160 students 25 % students failed. How many students passed to class 11th?

OPtion

1. 104
2. 108
3. 110
4. 130
5. 140
6. 120
7. 125
8. 135
9. 115
10. None of the above

Solution

Percentage of students passed to class X = (100 % - 25 %) of 160
= 75 % of 160
=> 75/100 × 160
=>12000/100
=> 120
Therefore, 120 students passed to class X

Correct Option: 6 Best Solution (0)

12 Oct 2021 Fraction

What approximate value will come in place of the question mark (?) in the following question? 15% of 240 = 20% of ? – 25% of 200

OPtion

1. 196
2. 430
3. 540
4. 635
5. 840
6. 420
7. 520
8. 530
9. 480
10. None of the above

Solution

15% of 240 = 20% of ? – 25% of 200
0.20 × ? – 0.25 × 200 = 0.15 × 240
0.20× ? – 50 = 36
0.20× ? = 86
? = 430

Correct Option: 2 Best Solution (4)

11 Oct 2021 Leak on tank

A tap can fill a Tank in 12 hours, but due to a leakage it took 18 hours to fill the Tank. If the Tank is full, in what time will the Tank become empty due to leakage?

OPtion

1) 48 hrs
2) 40 hrs
3) 28 hrs
4) 32 hrs
5) 42 hrs
6) 72 hrs
7) 34 hrs
8) 36 hrs
9) 30 hrs
10) None of these

Solution

1/12-1/18 = 3-2/36
=>1/36
=>36 hours

Correct Option: 8 Best Solution (2)

08 Oct 2021 Train

A 140m meters long train takes 12 seconds to cross Virat walking at 4 kmph in a direction opposite to that of the train. Find the speed of train.

OPtion

1) 49 kmph
2) 52 kmph
3) 55 kmph
4) 56 kmph
5) 62 kmph
6) 51 kmph
7) 57 kmph
8) 38 kmph
9) 53 kmph
10) None of the above

Solution

Speed of train relative to man = ( X + 4) Kmph = (X + 4) x 5/18 m/seconds.
140/ (X + 4) x (5/18) = 12
(140 x 18)/ (X + 4) 5 = 12
60X + 240 = 2520
X = 2280/60 = 38 Kmph

Correct Option: 8 Best Solution (2)

07 Oct 2021 Cards

A card is drawn from a set of playing cards, what is the probability that card drawn is a card having number greater than 5 or less than 9?

OPtion

1. 6/13
2. 9/13
3. 6/26
4. 3/26
5. 5/13
6. 3/13
7. 7/13
8. 5/26
9. 7/26
10. None of the above

Solution

Total number of cards = 52 i.e.
Total number of outcomes = 52
There will be a total of 12 cards between 5 and 9
Total number of favorable outcomes = 12
The probability of picking card between 5 and 9 = 12/52 = 3/13

Correct Option: 6 Best Solution (3)