M4maths Previous Puzzles

16 Jan 2019 Population

The population of rodents in a house doubles every day. Every day 25 rodents are killed. How many rodents are there if after every four days, the number of rodents becomes same again?

OPtion

1) 20
2) 5
3) 15
4) 6
5) 24
6) 12
7) 25
8) 16
9) 8
10) None of these

Solution

1st day - x
2nd day - (2x-25)
3rd day - [2(2x-25)-25]
4th day - 2[2(2x-25)-25] - 25 = 8x - 7*25

After fourth day the value becomes equal to the first day so 8x - 7*25 = x
Solving, we get x = 25

Correct Option: 7 Best Solution (0)

15 Jan 2019 Profit & Loss

Lalu sold his watch and sunglasses at a loss of 5% and gain of 5% respectively for 3600 to Bhalu. Bhalu sold the same sun glasses and watch at a loss of 4% and gain of 4% respectively for 3800. The price of watch and sun glasses respectively to Lalu in rupees were.

OPtion

1) 2650, 950
2) 2550, 1050
3) 2750, 850
4) 2850, 850
5) 2450, 1250
6) 2950, 750
7) 2450, 1050
8) 2650, 1050
9) 2850, 950
10) None of these

Solution

Let the CP of watch be Rs x and sunglasses be Rs y.

Lalu sold his watch and sunglasses at a loss of 5% and gain of 5% :
3600=95x/100 + 105y/100

Bhalu sold the same sun glasses and watch at a loss of 4% and gain of 4% respectively :
3800= 104x/100 + 96y/100

On solving,
y=744.44
x=2966.67

Option 10)

Correct Option: 10 Best Solution (0)

14 Jan 2019 Simple Interest

Nirav took a loan of Rs. 201900 from PNB with simple interest for as many years as the rate of interest. If he was supposed to pay Rs. 395724 as interest at the end of the loan period, what was the rate of interest?

OPtion

1) 11
2) 10
3) 11.5
4) 12.5
5) 14.5
6) 15
7) 16
8) 14.0
9) 15.5
10) None of these

Solution

SI = PRT/100
=> 395724 = (201900 *R*T)/100
As R=T so => 395724 = (201900 *R*R)/100

R^2 = 395724 * 100/201900 = 196
=> R= 14

Option 8)

Correct Option: 8 Best Solution (0)

11 Jan 2019 Speed and Distance

Rahmatullah could either walk or drive to office. The time taken to walk to the office is 11 times the driving time. One day, his wife took the car making him walk to office. After walking 2.5 km, he reached a temple when his wife called to say that he can now take the car. Ramanujam figured that continuing to walk to the office will take as long as walking back home and then driving to the office. Calculate the distance between the temple and the office in KMs.

OPtion

1) 5/2
2) 5/3
3) 7/2
4) 7/3
5) 2.0
6) 2.5
7) 6/2
8) 3.5
9) 3.25
10)None of these

Solution

Suppose the distance between his home and office is x km. Then, distance between his office and temple is (x – 2.5) km.
If he walks at a speed of y km/hr. Then his driving speed = 11y km/hour, as he is 11 times faster in car.

Then,
2.5/y + x/11y = (x – 2.5)/y
Or, 2.5 + x/11 = x – 2.5
or 10x/11 = 5
Or, x = 11/2
Finally, x – 2.5 = 11/2-5/2 = 6/2 = 3
Option 7)

Correct Option: 7 Best Solution (4)

MP    5 years AGO

If distance between office and temple is x kms and speed of walking is w kms per hr, then
x/w = 2.5/w +(x+2.5)/11w
solving it,
x=3 kms

Like? Yes (3) | No (1)  

Devendra Marghade   5 years AGO

Let the total distance from home to office be x km and driving speed be 'd' kmph, walking speed be 'w' kmph, then, x/w = 11*x/d => d=11w ---(i)
Also, (x-2.5)/w = 2.5/w + x/d ---(ii)
Substituting d=11w from (i) into (ii), we get
(x-2.5)/w = 2.5/w + x/(11w)
x-2.5 = 2.5 + x/11
x=5.5
So, distance between temple and office=x-2.5=5.5-2.5 = 3 km = 6/2 from the given options.
Answer: option 7)

Like? Yes | No (2)  

RAMADURAI NATESAN   5 years AGO

Let distance from home to office be = a.
let the walking speed be s and driving speed 11s.
As per given statement, following equation is formed:
(2.5/s)+ ( a/11s) = ( a - 2.5)/s. Solving, we get, a = 5.5 km.
Hence distance from temple to office is 5.5 - 2.5 = 3 0r 6/2.

Like? Yes | No (3)  

AASHRAY AJAY SHARMA   5 years AGO

Suppose the distance between his home and office is x km. Then, distance between his office and temple is (x - 2.5) km.
If he walks at a speed of y km/hr. Then his driving speed = 11y km/hour, as he is 11 times faster in car.

Then,
2.5/y + x/11y = (x - 2.5)/y
x = 5.5
Finally, x - 2.5 = 3 = 6/2
(Option 7)

Like? Yes | No (3)  

10 Jan 2019 Stocks

The market value of a 8.5% stock, in which an income of Rs. 1900 is derived by investing Rs. 11000, brokerage being 1/4 %, is:

OPtion

1) 48.25
2) 48.75
3) 49.00
4) 49.21
5) 48.50
6) 48.96
7) 48.85
8) 48.45
9) 48.60
10) None of these

Solution

For an income of Rs. 1900, investment = Rs. 11000

For an income of Rs. 8.5, investment = Rs. (11000/1900) * 8.5 = 49.21
For a Rs. 100 stock, investment = Rs. 49.21

Market value of Rs. 100 stock = Rs. 49.21 - 0.25 = Rs. 48.96

Option 6)

Correct Option: 6 Best Solution (0)

09 Jan 2019 Percentage

If P is 60% of Q, Q is 50% of R; R is 40% of S, S is 45% of T. Find P: T ?

OPtion

1) 3/50
2) 3/25
3) 7/50
4) 8/25
5) 4/25
6) 27/1000
7) 27/250
8) 27/500
9) 27/2000
10) None of these

Solution

P = 0.6 Q
Q= 0.25 R
So P = 0.6*0.25 R
R = 0.4 S
So, P = 0.6*0.5 * 0.4 S
S = 0.45*T
Again, P = 0.6* 0.5 * 0.4 * 0.45*T = 54/1000T
So P/T = 27/500
Option 8)

Correct Option: 8 Best Solution (4)

RISHIKA AGARWAL   5 years AGO

P=0.6Q
Q=0.5R
R=0.4S
S=0.45T
P=0.6*0.5*0.4*0.45T
P=0.054T
P:T = 27:500

Like? Yes | No   

Kariamal   5 years AGO

p=0.6*0.5*0.4*0.45t
p/t=0.054/1
p/t=27/500

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RAMADURAI NATESAN   5 years AGO

It is given that P = .6*.5*.4*.45*T = .054 T
Or 1000 P = 54 T . Or P/T = 54/1000 =27/500

Like? Yes | No   

MANISHA JADHAV   5 years AGO

p=60/100*50/100*40/100*45/100*T
T=T
P/T=27/500

Like? Yes | No   

08 Jan 2019 Ratio

Isha’s grandfather was 5 times older to her 4 years ago. He would be three times of her age 8 years from now. 7 years ago, what was the ratio of Isha’s age to that of her grandfather’s age?

OPtion

1) 2:5
2) 1:6
3) 1:4
4) 3:19
5) 3:17
6) 5:23
7) 4:7
8) 4:19
9) 5:18
10) None of these

Solution

Suppose Isha's grandfathers age is x and Isha's age is y

4 years ago
x-4 = 5*(y-4)
=> x = 5y - 16 --(i)

8 years from now
x+8 = 3*(y+8)
=> x = 3y + 16 --(ii)

(i) = (ii)
5y - 16 = 3y + 16
=> 2y = 32
=> y = 16
So x = 64

7 years ago
Age of Grandfather = 64 - 7 = 57
Age of Isha = 16-7 = 9
Ratio of ages = 9:57 = 3 : 19


Option 4)

Correct Option: 4 Best Solution (7)

AASHRAY AJAY SHARMA   5 years AGO

suppose that now their age is
x and y

4 years ago age was:x-4 , y-4
x-4=5(y-4)
after 8 years age would be
x+8=3(y+8)
on solving eq 1 and 2 we get x=64 y =16
so 7 years ago
(16-7)/(64-7)= 9/57
ratio is = 3:19--Option 4

Like? Yes | No   

sonypriyavalluru   5 years AGO

let Isha's present age be X and grandfather's be Y
four years ago Isha age is X-4
from given first condtion, 5(X-4)=Y-4
and 2nd condition, 3(X+8)=Y+8
solving those equations we get X=16; Y=64
now 7years ago their ages will be 16-7=9 and 64-7=57
now ratio is 9:57 = 3:19

Like? Yes | No   

Kariamal   5 years AGO

Isha's age=x, grandfather age=y
y-4=5(x-4)
y+8=3(x+8)
Solving above eqn.
x=16, y=64
7 years ago=9:57=3:19

Like? Yes | No   

Dr.Dipin Singh   5 years AGO

4 years ago, Ages were 12 years and 60 years.
8 years from now, ages will be 24 years and 72 years.
7 years ago, ages were 9 years and 57 years.
7 years ago, ratio of ages = 9/57=3/19

Like? Yes | No   

A.P.Singh   5 years AGO

Suppose 4 years ago, ages of grandfather and Isha were G and I respectively.
Then G=5I
G+12=3*(I+12)

solving , we get
I=12; G=60
7 years ago, Ages were 9 years and 57 years.
Hence ratio of ages 7 years ago = 9/57-3/19

Like? Yes | No   

Mouli Paul   5 years AGO

4 year ago
5(x-4)=y-4
after 8 year
3(x+8)=y+8
From two equ. we get 16 and 64
(16-7)/(64-7)=3:19

Like? Yes | No   

RISHIKA AGARWAL   5 years AGO

Let Isha's and Grandfather's present age be i and g resp.
4 yrs ago, Isha's age= i-4
her Grandfather's age=g-4
ATQ,
g-4=5(i-4)
Similarly, 8 yrs from now,
g+8 = 3 (i+8)
solving these 2 equations, we get, i=16 and g=64
Required Ans:
i-7:g-7=9:57
=3:19

Like? Yes | No   

07 Jan 2019 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 55 years now, what would be the son's age 4.5 years later?

OPtion

1) 31
2) 30
3) 32
4) 29
5) 28
6) 23
7) 24
8) 25
9) 26
10) None of these

Solution

Let the sons current age be x
So fathers age x years back when son was born => 55-x = x
Solving we get x = 27.5
4.5 Years later son's age = 27.5 + 4.5 = 32 years

Option 3)

Correct Option: 3 Best Solution (10)

G.S.Kantharao   5 years AGO

Father and son's age =55y,27.5y
After 4.5 y Son's age=32y
Right option is 3👈

Like? Yes (5) | No   

SAYAN CHATTERJEE   5 years AGO

F= 2s= 55
s= 27.5
So, son's age after 4.5 years is (27.5+4.5)= 32.
Option 3.

Like? Yes | No   

AASHRAY AJAY SHARMA   5 years AGO

At the time of birth father's age =x
2x=55=>x=27.5
After 4.5 years son's age is=27.5+4.5=32
Hence my option is 3

Like? Yes | No   

RAMADURAI NATESAN   5 years AGO

Let son's present age be = n . Since father's present age is 55
father's age at the time of his son's birth is 55 - n =n as per given given information.Thus 2n = 55 or n = 27.5. after 4.5 years,son's age will be 32.

Like? Yes | No   

Kariamal   5 years AGO

x=55-x
2x=55
x=27.5
4.5 years later=27.5+4.5
=32

Like? Yes | No   

Gargi   5 years AGO

let now soms age is x
then,
55-x=x
2x=55
x=27.5
then after 4.5 yrs 27.5+4.5=32

Like? Yes | No   

Navya   5 years AGO

let,x-->age of son at present i.e.,,,age of father at time of his son birth
2x=55
x=27.5 yrs
4.5 yrs later 32 yrs

Like? Yes | No   

MANISHA JADHAV   5 years AGO

let age of son=x
at the birthof son fathers age=x
but now fathers age=55=x+x
x=55/2=27.5
son's age after 4.5 years=27.5+4.5=32

Like? Yes | No   

udaychandu bachina   5 years AGO

As the age of father was the same as the age of son at the time of his birth which mean age of son should be half the age of father. So half of 55 will be 27.5. Adding 4.5 to 27.5 will give 32 as the age son after 4.5 years. Hence age of son will be 32 years after 4.5 years

Like? Yes | No   

Komal Mahangare   5 years AGO

55-x = x .... son age
2x= 55
x = 27.5
4.5 years later
son's age = 27.5 + 4.5 = 32

Like? Yes | No   

04 Jan 2019 Lift

Jack enters a lift on the 25th floor, which is going up @ 56 floors/min speed. At the same time Jill enters another lift on the 70th floor which is going down @ 64 floors/min speed. At what floor will

they be together?

OPtion

1) 41
2) 42
3) 43
4) 44
5) 45
6) 39
7) 47
8) 46
9) 48
10) None of these

Solution

Relative Speed = 56+64 = 120 floors/min
Relative Distance = 70 - 25 = 45 floors

Time to cover 45 floors = 45*60/120 = 22.5 seconds

Floors travelled by Jack in 22.5 seconds = (56/60)*22.5 = 21
Floors on which they will meet = 25 + 21 = 46th
Option 8)

Correct Option: 8 Best Solution (6)

G.S.Kantharao   5 years AGO

Let x is the floor they meet
(70-x)/64=(x-25)/56
(70-x)56=(x-25)64
3920-56x=64x-1600
120x=5520=>x=5520/120=46
Right option is 8👈

Like? Yes (6) | No   

SAYAN CHATTERJEE   5 years AGO

25+56x= 70-64x
x= 0.375
So, floor is 25+56*0.375= 46.
Option 8.

Like? Yes (2) | No   

RISHIKA AGARWAL   5 years AGO

They will meet after t time so Time is constt here.
D/S=constt
Distance ratio = Speed Ratio= 56/64=7/8
Total floor between 25th and 70th = 70-25= 45 (This is 15 *3)
So Jack will travel 7*3=21 floors from 25th and Jill will travel 8*3=24 floors from 70th to meet Jack.
So they will meet at 25+21 or 70-24 =46th Floor.

Like? Yes (1) | No   

Devendra Marghade   5 years AGO

Relative speed (in opposite direction)=56+64=120 floors/min.
Difference between them=70-25=45 floors.
So time taken to meet = 45/120 = 3/8 min.
Floors covered up by Jack in 3/8 min=56*3/8=21
Hence they meet at 25+21=46th floor.
Option 8)

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balaji   5 years AGO

after 22.5 minute they will together

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Kariamal   5 years AGO

Relative speed=56+64=120
Relative distance=70-25=45
So, 45/120*60=22.5
56/60*22.5=21
Floors on which they will meet=21+25=46

Like? Yes | No   

03 Jan 2019 Number of Cans

Chintu works at a soft drink company and was arranging some particular number of cylindrical aluminium soft drink cans in a square box but the box became full and there were 8 cans remaining to be put in. Then, he started arranging all Cans in a rectangular box where he could arrange 6 cans more along the length than the breadth after putting all the cans in the rectangular box. He found out that there was still space left for another 11 cans. What is the number of cans Chintu had if it is known that the number of cans were more than 15 and no can was put on top of another can?

OPtion

1) 25
2) 33
3) 34
4) 36
5) 55
6) 44
7) 45
8) 54
9) 56
10) None of these

Solution

In a square box the number of cans arranged along the length and breadth would be same.
In case of rectangular box, lets assume that number of cans along breadth is x then number of boxes along the length would be x+6
Total number of cans the rectangular box can take = x*(x+6)
Total number of cans Chintu was able to put in the rectangular box (as some empty space was remaining ) = x*(x+6) - 6 ---- (i)


Given that the number of cans are more than 15, hence 2 & 3 cans along the length are ruled out

Lets try with 4 cans along length of square box, total cans in box would be 16
Total number of cans which Chintu has = 16+8 = 24 ---- (ii)
(i = (ii)
x*(x+6) - 11 = 24
=> x^2 + 6x = 35
Trying to solve we realize that there is no such whole number which x can take

Lets try with 5 cans along length of square box, total cans in box would be 25
Total number of cans which Chintu has = 25+8 = 33 ---- (ii)
(i = (ii)
x*(x+6) - 11 = 33
=> x^2 + 6x = 44
Trying to solve we realize that there is no such whole number which x can take


Lets try with 6 cans along length of square box, total cans in box would be 36
Total number of cans which Chintu has = 36+8 = 44 ---- (ii)
(i = (ii)
x*(x+6) - 11 = 44
=> x^2 + 6x = 55
Solving we get x = 5

So total number of cans which Chintu had = x*(x+6) - 11 = 5(5+6) - 11 = 5*11 -11 = 44

Correct Option: 6 Best Solution (1)

G.S.Kantharao   5 years AGO

Let the side of the Square=x
x^2>15=> x^2=16/25/36/...
Length and breadths are l and b where l=b+6
l*b=b(b+6)=16+8+11/25+8+11/36+8+11/...
b^2+6b=35/44/55/...
b^2+6b-55=0(55 gives real solution)
(b-5)(b+11)=0
Breadth =5
Length=11
Area =55
Chintu had at first =55-11=44
My option is 6👈

Like? Yes (7) | No (2)