5. In a history examination, the average for the entire class was 80 marks.If 10% of the students scored 95 marks and 20% scored 90 marks,what was the Average marks of the remaining students of the class?
A. 73
B. 74
C. 72
D. 75

• Let the number of students be 10
  then 10% 0f them is 1 scored=95
  20% " 2 scored=2*90=180
  10*80 - (95+180) = 525
  Avg= 525/7= 75
  
  
• 9 years agoHelpfull: Yes(7) No(1)
• let the no of students=100
  then 10*95+20*90+70*x=8000
  so x=75
• 9 years agoHelpfull: Yes(5) No(1)
• let total no of students =x
  so total marks =80*x
  now 10% of students scored 95 so total marks obtained by 10% students is 0.1*x*95=9.5*x
  (as x*10%=0.1x)
  20% of students scored 90 marks so total marks obtained by 20% students is 0.2*x*90=18*x
  so total marks obtained by rest0.7 students is (80*x-9.5*x-18*x=52.5x)
  so avg marks of rest students is 52.5x/0.7x=75
  
• 8 years agoHelpfull: Yes(2) No(1)
• let us assume that total no. of students = 100 (for simplicity)
  it is given that average of marks =80
  so total marks of students = 100*80=8000
  it is also given that 10% of students scores =95
  so total marks obtained by 10% or 10 students =95*10=950
  it is also given that 20% of students scores=90*20=1800
  so total marks obtained by 20% or 20 students=1800
  so remaining students =70 or 70 %
  so marks obtained by remaining students= 8000-950-1800=5250
  so average marks of remaining students = 5250/70=75
  so 75 is the correct answer
• 9 years agoHelpfull: Yes(1) No(0)
• if total 100 students then out of them 10 scored 95, 20 scored 90 and let rest of them i.e. 70 scored a marks.,then
  80=((10x95) +(20x90) + (70xa))/100
  a=75
• 9 years agoHelpfull: Yes(1) No(0)
• 75
  8000-950-1800=5250/70=75
• 8 years agoHelpfull: Yes(1) No(0)
• Whether infosys result declared or not.plz inform.which was on 27 dec at kolkata
• 10 years agoHelpfull: Yes(0) No(3)
• consider their are 10 students in the class .given
  10x=800
  10% ,20% in 10 members is 1,2
  7x+1(95)+2(90)=800
  7x=525
  x=75marks is average for rest of the students
• 9 years agoHelpfull: Yes(0) No(0)
• option d. 75.
  
• 9 years agoHelpfull: Yes(0) No(0)
• let the strength be 10,total marks obtain by student is 80*10=800, 10% (1 student) get 95*1=95 marks and 20%( 2) get 2*90=180 marks,total marks left=800-95-180=525 and students left=7. average =525/7=75
• 8 years agoHelpfull: Yes(0) No(0)
• D.75
  as per given conditions we can write an equation:-
  x*10/100*95+x*20/100*90+x*70/100*y=x*80
  where,
  x=total number of students in the class
  y=average of remaining 70% students
• 8 years agoHelpfull: Yes(0) No(0)
• assume that there are 100 students in the class
  
  out of 100 only 10 got 95
  and 20 got 90
  remaining 70 students
  
  (0.10*95)+(0.20*90)+(x*70)=80
  9.5+18+(x*70)=80
  x*70=80-27.5
  x*70=52.5
  x=52.5/70
  x=0.75
  
  and the answer is option D. 75
• 7 years agoHelpfull: Yes(0) No(0)
• Let the number of students in the class be 100 and let this required average be x.
  Then, (10 * 95) + (20 * 90) + (70 * x) = (100 * 80)
  => 70x = 8000 - (950 + 1800) = 5250
  => x = 75.
• 7 years agoHelpfull: Yes(0) No(0)
• let number of students 100
  10% of 100=10 ,so 10 student secure 95 marks.
  20% of 100=20 ,so 20 student secure 90 marks
  remaining 70 students average is let x
  so ((10*95+20*90+70*x)/100)=80
  =>70x= 5250
  =>x=75
• 6 years agoHelpfull: Yes(0) No(0)
• let no. of students =10
  10% of 10 =1
  so one has scored= 95
  20% of 10= 2
  so two student has scored =90
  so
  average marks required = 80
  10*80 - (95+180) = 525
  average = 525/7=75
• 5 years agoHelpfull: Yes(0) No(0)