Ratio of boys to girls 4:5 , when 100 girls leave the school the ratio becomes 6:7 . How many boys are there ?
a) 1600
b) 1200
c) 600
d) 800

• B/G = 4/5 => G = 5B/4 -----(1)
  
  B/(G-100) = 6/7 ------(2)
  => 7B = 6G -600
  => 7B = 6*5B/4 -600
  => 28B = 30B -2400
  => 2B = 2400
  => B = 1200
  
  b) 1200
• 10 years agoHelpfull: Yes(50) No(0)
• ye bakwaas ques elitmus ka hai kya? elitmus ka standard kab se itana low ho gya ....
• 10 years agoHelpfull: Yes(19) No(2)
• answer is b)1200 .because only 1200 is divided in 1st radio by 4 and in 2nd radio by 6 so this is right answer.
  and if we take 1200 for boys then in 1st condition girls are 1500 and in 2nd condition 1400.
• 10 years agoHelpfull: Yes(3) No(0)
• x/y = 4/5 => x=4/5*y.....(1)
  now,
  100 girls left so the new ratio became:
  x/(y-100)=6/7 ...(2)
  solving 1 & 2,
  x=1200 so 1200 boys is the answer.
• 10 years agoHelpfull: Yes(1) No(0)
• 4x/(5x-100)=6:7
  =>x=300
  boys=4*300=1200
• 10 years agoHelpfull: Yes(1) No(0)
• boys=4x
  girl=5x
  4x/(5x-100)=6/7
  x=300
  girls=5*300=1500
• 10 years agoHelpfull: Yes(0) No(4)
• 4x/5x-100 = 6/7
  28x = 30x-600
  x = 300
  so boys = 4x = 4*300 = 1200
• 10 years agoHelpfull: Yes(0) No(0)
• Let number of boys and girls be x and y respectively.As given,x/y=4/5.now x/y-100=6/7.when we solve second equation we get y=1500.also from first equation we can say x=4y/5.Substituting the value of y=1500 in x=4y/5,we get x=1200 which is the number of boys.Therefore number of boys=1200.
• 10 years agoHelpfull: Yes(0) No(0)
• 1200
  
  b/g=4/5;
  b/g-100=6/7
  on solving these two equation
  we got b=1200
• 10 years agoHelpfull: Yes(0) No(0)
• 4x/5x-100=6/7
  x=300
  4*300=1200
  
• 9 years agoHelpfull: Yes(0) No(0)
• 1200/4=300
  1200/6=200
  difference is 100 hence answer is 1200. No other option provide you with a difference of 100
• 9 years agoHelpfull: Yes(0) No(0)
• boys=4x
  girls=5x
  so
  4x/5x-100=6/7
  28x=30x-600
  2x=600
  so x=300
  initially boys are 4x
  sustitute 300 in x
  so 4*300
  1200
  
  
• 9 years agoHelpfull: Yes(0) No(0)
• Let boys be 4x and girls be 5x.
  According to question.
  4x / (5x -100) = 6/7.
  On solving this we get x=300.
  Then boys is 4*300 = 1200
• 4 years agoHelpfull: Yes(0) No(0)