30-3

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by beny » Sat Aug 25, 2007 2:37 pm
Answer is E.

First, solve how many apples and oranges she took initially:

[40x+60(10-x)]/10=56
x=2

Thus she took 2 apples and 8 oranges.

Then solve for how many oranges she must have (provided that she has 2 apples) in order for the average price to be 52 cents:
[(2*40)+60y]/(2+y)=52
y=3

Thus, she must have 2 apples and 3 oranges. She initially had 8 oranges, so she has to put back 5.

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by agps » Sat Aug 25, 2007 2:39 pm
answer is E (5 oranges)

first calculate how many oranges and appleas you have,
A+O=10
(40*A+60*O)/10=56

this gives 2 Apples and 8 Oranges
80+480/10 =560/10 = 56

if you remove 1 orange you get 80+420/9=500/9 = 55.5
if you remove 2 oranges you get 80+360/8 = 440/8 = 55
if you remove 3 oranges you get 80+300/7 = 380/7 = 54.2...
if you remove 4 oranges you get 80+240/6 = 320/6 = 53,3...
if you remove 5 oranges you get 80+180/5 = 260/5 = 52

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by agps » Sat Aug 25, 2007 2:57 pm
:oops:
beny got to it first.....

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by magical cook » Sun Aug 26, 2007 4:45 pm
Thanks the answer is E :)