Expert: Lynn Houston - 2/17/2010

Question
QUESTION: A MAN SOLD 10 EGGS FOR RS5 AND GAINED 20%.HOW  MANY  EGGS  DID HE BUY  FOR RS5?

ANSWER: let x = the number of eggs the man bought for RS5 so 5/x is the price per egg.  He sold 10 eggs for 5, or .5/egg. So

.5 - 5/x = .20(5/x)
.5x - 5 = 1  
.5x = 6
x = 12

to test your answer...   5/12 = .41666 so he paid RS 4.1666 for 10 eggs.  10 eggs were sold for .5 per egg or RS5.  4.1666 + 20% = 5



 





---------- FOLLOW-UP ----------

QUESTION: A GOT  32% MARKS IN AN EXAM AND FAILED BY 40 MARKS.B  GOT  37% MARKS AND GOT 20 MARKS MORE  THAN PASS MARKS.FIND  TOTAL MARKS.

ANSWER: Ok, let x = total # of "marks" possible (just fyi, I have no idea what marks are)

Just looking at the problem, you can see that 20 marks = 5% of the test, therefore the total test is 400 marks.  If you want to work it out algebraically...

A's score, a/x = .32 and b's score b/x = .37
and b = a+20
solve the first eq for x  (a = .32x)

fill in the value of b into b's score

a+20/x = .37  fill in the value of a into the eq.

(.32x +20)/x = .37  multiply by x
.32x + 20 = .37x
20 = .05x
x = 400



---------- FOLLOW-UP ----------

QUESTION: BUT,  THE  CORRECT ANSWER IS 444.PLEASE SOLVE IT  AGAIN.THANKS

Answer
I don't have to solve it again...

400 x .32 = 128
400 x .37 = 148

A who got 32% on his test got 128 marks and b who got 37% on his test got 148 or 20 marks more. Maybe knowing what "marks" are or what the "failure" rate is, makes a difference, but 400 is an accurate answer to the question.