Latest Elitmus Aptitude Question SOLUTION: Mr. A starts using shed and shoulder shampoo. due to work pressure he lost 1/4th of his hair every year. after how many years will he having 25% less hair than what he had at the s

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(#M40035326) ELITMUS Numerical Ability question percentage Keep an EYE

Mr. A starts using shed and shoulder shampoo. due to work pressure he lost 1/4th of his hair every year. after how many years will he having 25% less hair than what he had at the start of usage of shampoo?
A) 3
B) 4
C) 5
D) 7

Asked In Elitmus jitendra kumar (10 years ago)

Unsolved Read Solution (10)

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Read Solution (10) :

jitendra kumar  (10 years ago)

let Mr.A has x amount of hair...
for 1st yr end he has (x- x/4) = 3x/4
for 2nd yr end he has (3x/4 - 3x/16) = 9x/16
for 3rd yr end he has ( 9x/10 - 9x/64) = 27x/64
or 4th yr end he has (27x/64 - 27x/256) = 81x/256
for 5th yr end he has (81x/256 - 81x/1024) = 243x/1024
now 243x/ 1024 < 256x/1024
i:e; 243x/1024 < x/4
So ANS = 5 yrs

Is this solution Helpfull? Yes (31) | No (8)  

RAKESH  (10 years ago)

C) 5 years

let Mr. A has x amount of hair
Mr. A looses 1/4th of his hair every year i.e @ 25%

let after t years he will be having 25% of starting

x(1- 25/100)^t = x*25/100
=> (3/4)^t = 1/4
=> t(log3 - log4)= -log4
log2=.301 & log3=.477
=> t = 4.8
after 4.8 years Mr. A will he having only 25% of hair
after 5 years Mr. A will he having less than 25% of hair of starting.

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pushpender  (9 years ago)

ans is 1 year

all option r wrong

Is this solution Helpfull? Yes (7) | No (1)  

kasthuri  (10 years ago)

first yr he lost 25%,2nd yr ll be 50 and in third 75%..
now having 25%,acc to qusn less than 25% means in 4th yr only he have..
Ans >4

Is this solution Helpfull? Yes (4) | No (7)  

Abhilash Sahu  (9 years ago)

This question is wrong.
As 1/4th hair he losses every, so 1/4th=25% every year.
So acc to question it is asking dt in how many year he ll loss 25% hair.
So the ans ll b in 1 yr, which is not in d option.
Ans is 1 yr.

Is this solution Helpfull? Yes (4) | No (1)  

Mani kandan  (10 years ago)

hai rakesh, how it become
x(1- 25/100)^t = x*25/100
(3/4)^t = 1/4
=> t(log3 - log4)= -log4
log2=.301 & log3=.477
=> t = 4.8

please explain

Is this solution Helpfull? Yes (1) | No (2)  

Lakshminarayana  (10 years ago)

1st year 100% he have
at the end of year he have 100%-25%=75%
at the end of 2nd year 75% -25%=50%
at the end of 3rd year 50% -25%=25%
so after 4 years he have 25% less hair
Ans: B

Is this solution Helpfull? Yes (1) | No (7)  

jitendra  (8 years ago)

let 1
lost 25%
1st year =1-/4=3/4
2st year =3/4 - (3/4)(1/4)=9/16
3st year =9/16 - (9/16)(1/4)=27/64
G.P.
3/4,9/4,27/4............................
total=(3/4)/(1-1/4)
total=3

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SUDHAKAR SRIVASTAVA  (9 years ago)

after 3 years

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amar deep mishra  (9 years ago)

ans: c) 5

(20*10 + 15*8 + x*4)/(20+15+x) = 8.5
(200+120+4x)/(35+x)=8.5

after solving this step you will find

x=5

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