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

• 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
• 10 years agoHelpfull: Yes(31) No(8)
• 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.
• 10 years agoHelpfull: Yes(28) No(10)
• ans is 1 year
  
  all option r wrong
• 10 years agoHelpfull: Yes(7) No(1)
• 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
• 10 years agoHelpfull: Yes(4) No(7)
• 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.
• 10 years agoHelpfull: Yes(4) No(1)
• 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
• 10 years agoHelpfull: Yes(1) No(2)
• 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
• 10 years agoHelpfull: Yes(1) No(7)
• 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
  
• 9 years agoHelpfull: Yes(1) No(0)
• after 3 years
• 10 years agoHelpfull: Yes(0) No(1)
• 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
• 10 years agoHelpfull: Yes(0) No(2)