The average of a list of 6 numbers is 20. If we remove one of the numbers, the average of the remaining numbers is 15. What is the number that was removed?

• Removed number is 45
  
  soln:
  6*20=120
  new average,
  15*5=75
  so
  removed number is (120-75)=45
• 9 years agoHelpfull: Yes(10) No(1)
• let us assume sum of 6 numbers is x.
  so equation is x/6=20
  x=120--------(1)
  and let us consider r is number which removed so it remove from the sum of 6 numbers and left only 5 number
  so average of 5 number is eq. (x-r)/5=15
  x-r=75-----------(2)
  from (1) and (2)
  x-x+a=120-75
  then a=45
  so answer is 45.
  
• 9 years agoHelpfull: Yes(2) No(0)
• 45
  x1+x2+x3+x4+x5+x6=120
  x1+x2+x3+x4+x5=75
  x6=120-25=45
• 9 years agoHelpfull: Yes(0) No(0)
• sum=avg*num
  sum=20*6=120
  after removing num
  sum=15*5=75
  removing num=120-75=45
• 9 years agoHelpfull: Yes(0) No(0)
• 45
  6 nos sum = 20*6 =120
  120-x =15*5=75
  x =45
• 9 years agoHelpfull: Yes(0) No(0)
• effective change 5*6=30
  the no=30+15
• 9 years agoHelpfull: Yes(0) No(0)
• 6*20=120
  5*15=75
  no.=120-75=45
• 9 years agoHelpfull: Yes(0) No(0)
• let the total be x
  when the avg is 20 and nos. are 6, then total = 6*20=120
  now one no is removed hence nos . are 5 and avg is 15,
  therefore new total = 15*5=75,
  therefore the removed no is (120-75)=45
• 9 years agoHelpfull: Yes(0) No(0)
• average=sum/count, sum(6 nos)=120,sum(5 nos)=75
  number is 45
• 9 years agoHelpfull: Yes(0) No(0)
• (x+y)/6=20 , where x is addition of 5 no. and y is the 6th no.
  and
  y/5=15 then x=45
  so that no. is 45
• 9 years agoHelpfull: Yes(0) No(0)
• 120-x=15*5
  x=45
• 9 years agoHelpfull: Yes(0) No(0)
• solution:
  6*20=120
  5*15=75
  so, the removed number is (120-75)=45
• 9 years agoHelpfull: Yes(0) No(0)
• sum1=20*6 and sum2=sum1-x=15*5
  20*6 -x = 15*5
  x= 120 - 75= 45
• 9 years agoHelpfull: Yes(0) No(0)
• 20*6-15*5=45
• 9 years agoHelpfull: Yes(0) No(0)
• 20*6=120
  15*5=75
  120-75=45
• 9 years agoHelpfull: Yes(0) No(0)
• (6*20)-(5*15)=45
  
• 9 years agoHelpfull: Yes(0) No(0)
• 42.5 is right answer
• 9 years agoHelpfull: Yes(0) No(0)
• 20+5*5=45 .the no is giving the avg of 20.also the no is able to give 5 to each remainng five no so no is
  
• 9 years agoHelpfull: Yes(0) No(0)
• 20*6=120
  5*15=75
  120-75=45
• 8 years agoHelpfull: Yes(0) No(0)
• (A+rem)/6=20..A+rem=120
  rem/5=15..rem=75.and
  A=45..
• 8 years agoHelpfull: Yes(0) No(0)
• avg=sum/no of item
  20=x/6
  x=6*20=120
  avg=sum/no of item
  15=y/5
  y=15*5=75
  the required no is =120-75=45
• 7 years agoHelpfull: Yes(0) No(0)