The total expense of a boarding house are partly fixed and partly variable with the number of boarders. The charge is Rs.70 per head when there are 25 boarders and Rs.60 when there are 50 boarders. Find the charge per head when there are 100 boarders.

a) 65

b) 55

c) 50

d) 45

• let the fixed be a and variable be k.
  so, a+25k=70*25
  and, a+50k=60*50
  solving these we get k=50 and a=500
  so for 100 boarders it will be
  500+100*50=5500
  per head= 5500/100 =55(ans B)
• 13 years agoHelpfull: Yes(13) No(0)
• ans:50
  if the number of heads increased by 2 times then he decreases the charge by 10
• 13 years agoHelpfull: Yes(2) No(7)
• x+25y=70*25=1750 x+50y=60*50=3000
  solve the both => 25y=1250
  y=50 ,x=500 => 500+100*50=>5500/100=55
  ans is 55
• 13 years agoHelpfull: Yes(2) No(0)
• if the number increases from 1st case to 2nd by 100% the cost gets low by rs 10 hence if 50*2=100,then again rate gets reduced by 10 from 2nd case as 50
• 13 years agoHelpfull: Yes(0) No(2)
• suppose fixed amount is x and variable amount is y.
  x+25y=70*25=1750.....(1)
  x+50y=60*50=3000....(2)
  subtract 1st from 2nd-we get---- 25y=1250
  we get y=50 and x+25*50=1750
  x=1750-1250=500
  so for 100 boarders it will
  x+100*y=500+100*50=5500
  per head= 5500/100 =55
• 12 years agoHelpfull: Yes(0) No(0)
• equation for rate per head can be given as
  rate per head=k/x +y,
  where x= no. of boarders and y=fixed rent.
  so in case of 25 boarders
  70=k/25 +y
  in case of 50 boarders
  60=k/50 +y
  solving both equations we get
  k=500 and y=50
  
  
  so required rate=500/100 +50=55
  answer=55
• 12 years agoHelpfull: Yes(0) No(0)
• Let fixed cost=a, variable cost=k
  We can write a+25k=70*25=1750
  a+50k=3000
  We get k=50
  then a=3000-(50*25)=500
  Charge per head= (500+100*50)/100 = 55
  
• 9 years agoHelpfull: Yes(0) No(0)