M4maths Previous Puzzles

17 Mar 2021 LCM & HCF

The HCF and LCM of two numbers is 12 and 600 respectively. If one of the number is 24, then the other number will be?

OPtion

1) 350
2) 420
3) 440
4) 460
5) 280
6) 300
7) 310
8) 250
9) 450
10) None of the above

Solution

Let the number is N.
Since the product of the number = LCM x HCF
N x 24 = 12 x 600
N = 300

Correct Option: 6 Best Solution (3)

16 Mar 2021 Swimming Pool

A swimming pool is 100 ft. by 50 ft. and has an average depth of 6 ft. By the end of an average summer day, the water level drops an average of 1 ft. How many cubic feet of water are lost each day?

OPtion

1) 2000 cubic feet
2) 2500 cubic feet
3) 2800 cubic feet
4) 3000 cubic feet
5) 3200 cubic feet
6) 3500 cubic feet
7) 3600 cubic feet
8) 3400 cubic feet
9) 4000 cubic feet
10) None of the above

Solution

When the pool is full in the morning, it has
100 ft. x 50 ft. x 6 ft. =30,000 cubic feet of water.
But it loses 1/6 of its water per day, from a depth of 6 ft. to 5 ft.
So, 1/6 of 30,000 is 5,000 cubic feet.

Correct Option: 10 Best Solution (0)

15 Mar 2021 sequence

What is the 500th number of the below sequence?
5 11 17 23 29 35 41 . . .

OPtion

1) 2555
2) 2599
3) 2899
4) 2655
5) 2999
6) 2799
7) 3000
8) 2099
9) 3099
10) None of the above

Solution

an = a + (n-1)d
a = 5, d = 6
a500 = 5 + (500 – 1 ) 6
= 5+ 499 x 6 = 2999

Correct Option: 5 Best Solution (3)

12 Mar 2021 Majority

100 students are majoring in math, business, or both. 72% of the students are business majors, and 58% are math majors. How many students are majoring in both?

OPtion

1) 28%
2) 42%
3) 70%
4) 40%
5) 35%
6) 30%
7) 28%
8) 32%
9) 46%
10) None of the above

Solution

If 72% are business majors, then 28% are not.
If 58% are math majors, then 42% are not.
So, 28+42 = 70% of the students, are not majoring in both.
So, 100 – 70 = 30% students are majoring in both.

Correct Option: 6 Best Solution (2)

11 Mar 2021 AVERAGE

Raina makes a score of 110 runs in 22nd inning of his career and thus increases his average by 4. Find his average after 22nd inning.

OPtion

1) 26
2) 39
3) 34
4) 28
5) 22
6) 44
7) 25
8) 21
9) 31
10) None of the above

Solution

Let the average after 22nd inning = x
Then, average after 21st inning = (x-4)
21 ( x – 4) + 110 = 22x
21x – 84 + 110 = 22x
X = 26

Correct Option: 1 Best Solution (2)

10 Mar 2021 AP

Find the 7th term of the A.P. 8, 5, 2, –1, –4,…..

OPtion

1) 10
2) 8
3) -8
4) -9
5) -12
6) 12
7) -10
8) 9
9) 6
10) None of the above

Solution

Here a = 8, d = 5 – 8 = –3
Now t7 = 8 + ( 7 – 1 ) d
= 8 + ( 7 – 1 ) (– 3 )
= 8 + 6 (– 3 )
= 8 – 18
= – 10

Correct Option: 7 Best Solution (1)

09 Mar 2021 Loss

By selling 88 trucks a vendor loses the selling price if 2 trucks. Find his percentage loss.

OPtion

1) 2.5%
2) 3.5%
3) 3.22%
4) 2.22%
5) 4.22%
6) 2.88%
7) 2.65%
8) 3.88%
9) 4.88%
10) None of the above

Solution

Let the SP of 1 truck = ₹1
SP of 88 trucks = ₹88
And loss = ₹2
CP = SP + Loss
CP = 88 + 2 = ₹90
% Loss = 2/90 x 100 = 2.22%

Correct Option: 4 Best Solution (2)

08 Mar 2021 AVERAGE

The average age of a 52 members of a village is 32 yrs. If the age of the youngest member be 7 yrs., then what was the average age of the village at the birth of the youngest member?

OPtion

1) 25 yrs.
2) 23.6 yrs.
3) 24.48 yrs.
4) 23.85 yrs.
5) 22.46 yrs.
6) 21.80 yrs.
7) 24.66 yrs.
8) 26.50 yrs.
9) 28 yrs.
10) None of the above

Solution

Total ages of all members
= 52 x 32 = 1664 yrs.
7 yrs. ago, total sum of ages = 1664 – (52 x 7) = 1300 yrs.
But at that time there were 51 members in the family.
Average at that time
= 1300/51 = 25.49 yrs.
Hence option 10.(None of the above) is the correct answer.

Correct Option: 10 Best Solution (0)

05 Mar 2021

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

Suppos 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 (1)

04 Mar 2021 Percentage

5 liters of HCL is added to 15 liter of a solution containing 40% of DI water. The percentage of DI Water in the new mixture is

OPtion

1) 35%
2) 38%
3) 42%
4) 46%
5) 30%
6) 28%
7) 25%
8) 32%
9) 45%
10) None of the above

Solution

We have a 15-litre solution containing 40% of DI water in the HCL.
=> Quantity of DI water in the solution =(15* 40)/100= 6
Now 5 litre of HCL is added to the solution.
=> Total quantity of the new solution = 15 + 5= 20
Percentage of DI water in the new solution = 6*100/20
= 600/20 = 30%

Correct Option: 5 Best Solution (3)