M4maths Previous Puzzles

14 Apr 2020 Number

What is a two-digit square number whose sum of digits is also a square number?

OPtion

1) 80
2) 91
3) 79
4) 82
5) 83
6) 78
7) 25
8) 36
9) 16
10) None of these

Solution

3 + 6 = 9,

Correct Option: 8 Best Solution (3)

13 Apr 2020 Age

A father said to his son, "I was as old as you are at the present at the time of your birth". If the father's age is 48 years now, what was the son's age nine years back?

OPtion

1) 24
2) 18
3) 16
4) 17
5) 15
6) 21
7) 22
8) 14
9) 19
10) None of these

Solution

Father Age = 48
Let father's age be x when the son was born
So present age of son x

As per question 49-x = x
So x = 24
Age of son 9 years ago = 24-9 = 15

Correct Option: 5 Best Solution (2)

10 Apr 2020

Raghunandan has built a cubical water tank with lid for his apartment with each outer edge equal to 1.5 m. He gets the outer surface of the tank including the base, covered with square italian tiles of side 25 cm. Find how much he would spend on tiles if the cost of tile is Rs 7200 per dozen?

OPtion

1) 126600
2) 128600
3) 129600
4) 127600
5) 108000
6) 129400
7) 128400
8) 130600
9) 131600
10)None of these

Solution

The edge of the tank = 1.5m = 150cm

Then,

Surface area of the tank excluding lid = 5 x 150^2 =

Area of each title = 25^2

Number of tiles required = 5* 150*150/(25*25) = 180

Cost of 12 tiles = 7200
Cost of 1 tile = 7200/12 = 600

Therefore, the cost of 180 tiles = 180 x 600 = 108000

Correct Option: 5 Best Solution (0)

09 Apr 2020 Time and Work

Amar and Akbar can do a given work in 8 days, Akbar and Anthony do the same work in 12 days and Amar, Akbar, Anthony complete it in 6 days. In how many days can Amar and Anthony finish it?

OPtion

1) 8
2) 7.5
3) 4
4) 16
5) 7
6) 9
7) 6
8) 5
9) 10
10) None of these

Solution

Amar + Akbar = 8 days

Akbar + Anthony = 12 days

Amar + Akbar + Anthony = 6 days

Amar = 1/6 - 1/12 = 12-6/12*6 = 6/12*6= 1/12

Anthony = 1/6 - 1/8 = 8-6/8*6 = 2/48 = 1/24

Amar + Anthony = 1/12 +1/24 = 24+12/ 24*12 =36/24*12= 1/8
=> 8 days.

Correct Option: 1 Best Solution (3)

08 Apr 2020 Profit and Loss

A vendor order 2000 pieces of a particular Chinese component at Rs.25 per piece. According to his estimates, even if 5% fail to pass the quality tests,then he will make a profit of 25%. However,as it turned out,50% of the components were rejected. What is the loss to the vendor?

OPtion

1) 11000
2) 11500
3) 11750
4) 12000
5) 12500
6) 12750
7) 13000
8) 13500
9) 13750
10) None of these

Solution

Total number of component = 2000.

If 5% competent found to be defective, then,

No. of non-defective component = 2000 - 5% of 2000 = 1900.

So,
Selling price of 1900 component = 1900 * 25 = 47, 500.

This content 25% profit of the vendor.

Let total price of the component = X.

SP = 47500

X + 25% of X = 47500

(100X +25X) /100 = 47500.

125X = 4750000

X = Rs. 38,000.

If 50 component ie 1000 components are deffective. then

Total collection = 25 *1000 = 25000.
Loss = 38000 - 25000 = Rs. 13,000.

Correct Option: 7 Best Solution (2)

07 Apr 2020 Numbers

What is a two-digit square number that is the product of two unique square numbers greater than one?

OPtion

1) 32
2) 24
3) 38
4) 18
5) 42
6) 49
7) 64
8) 81
9) 25
10) None of these

Solution

4 x 16 = 64.

Correct Option: 7 Best Solution (1)

06 Apr 2020 Swim

If Michael can swim downstream at 6kmph and upstream at 2kmph.
What is his
speed in still water?
Round decimals to the nearest hundredths.

OPtion

1) 8.00mps
2) 4.00mps
3) 2.00mps
4) 6.00mps
5) 5.00mps
6) 7.00mps
7) 10.00mps
8) 1.11mps
9) 12mps
10) None of these

Solution

Let speed of Micahel be M kmph
and stream be S kmph
M+S = 6kmph
M-S = 2kmph

Solving we get 2M = 8 kmph
=> M = 4kmph = 4*5/18 mps = 1.111111mps

Correct Option: 8 Best Solution (3)

03 Apr 2020 Simple Interest

What would be the simple interest on an amount of Rs 2020 invested for 3 years at the simple interest rate of 4%?

OPtion

1) 2520
2) 2262.4
3) 2462.4
4) 2362.4
5) 2162.4
6) 315.4
7) 242.4
8) 3750.5
9) 3501.9
10) None of these

Solution

SI = PRT/100 = 2020*4*3/100= 242.4

Correct Option: 7 Best Solution (5)

02 Apr 2020 Profit & Loss

A Chinese bike is is sold at a certain price. By selling it at two third of that price one loses 10%.
Find the gain
percent at original price.

OPtion

1) 20%
2) 65%
3) 35%
4) 45%
5) 50%
6) 42%
7) 25%
8) 49%
9) 27%
10) None of these

Solution

Let the original SP be S
and CP be C

SP at 2/3rd price = (2/3)S
Loss =>
[( C - 2/3)S] x 100 / C
= 10
=> (C - (2/3)S ) x 100 = 10C
=> 200S/3 = 90C
=> S = 27C/20

Gain at original price =
=> (27C/20 - C) x100 /C
= > 7*100/20
=> 35%

Correct Option: 3 Best Solution (0)

01 Apr 2020 Revolutions

A wheel has a diameter of 175 cm. How many revolutions of the wheel are needed to cover a distance of 302.5 m ?

OPtion

1) 26.5
2) 25.5
3) 24.5
4) 35.5
5) 55.0
6) 34.5
7) 71.5
8) 50.5
9) 55.5
10) None of these

Solution

Circumference of wheel = 2piR = 175 x 22/7 = 550 cm

Distance = 320.5 m = 30250 cm

Revolutions = 30250/550 =55

Correct Option: 5 Best Solution (2)