the boys and girls are in the ratio 3:2.if 20% of the boys and 25% of girls are adults.the percentage of students who are not adults?

• Ans:-78%
  total no of students =x
  no of boys=3x/5
  no of girls=2x/5
  
  no of boys adult=20*3x/100*5=3x/25
  no of girls adult=25*2x/100*5=x/10
  
  total no of adult students are=3x/25+x/10=11x/50
  no of stuent who are not adult are=x-11x/50=39x/50
  % of students who are not adult are=39x*100/x*50=78%
• 10 years agoHelpfull: Yes(1) No(0)
• 78% are not adults..
  let t,x,y are total,boy,girl students..
  boys=(3/5)t
  girls=(2/5)t
  total adults=(20/100)x+(25/100)y
  submit x value in above equation
  =(1/5)(3/5)t+(1/4)(2/5)t
  =(22/100)t
  so 22% of students are adults
  remaining are not adults
• 10 years agoHelpfull: Yes(0) No(0)
• let there are 150 students.
  the boys and girls are in the ratio 3:2
  So,90 boys and 60 girls.
  20% of the boys are adult.=>20% of 90=18
  25% of the girls are adult.=>25% of 60=15
  Total adults=33(out of 150)
  Not adult=117.
  150 : 100
  117 : ?
  (117*100)/150=78%
• 10 years agoHelpfull: Yes(0) No(0)
• Let us consider boys:girls = 3:2 means boys = 3*k and girls = 2*k, where k is an arbitrary constant such that the ratio relation remains same. Therefore, we can write: total students = boys+girls = 5*k.
  total adults = 20% of boys + 25% of girls = 20% * 3*k + 25% * 2*k
  = 1.1*k
  %not adults = (total student - total adult) / total student *100%
  = (5*k-1.1*k)/(5*k)*100% = 78% ANS.
• 10 years agoHelpfull: Yes(0) No(0)