SOLUTION: Sharing cost. The members of a flying club plan to share equally the cost of a $200,000 airplane. The members want to find five more people to join the club so that the cost per pe

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Question 281982: Sharing cost. The members of a flying club plan to share equally the cost of a $200,000 airplane. The members want to find five more people to join the club so that the cost per person will decrease by $2000. How many members are currently in the club?
Found 2 solutions by josmiceli, ptaylor:
Answer by josmiceli(19441) About Me  (Show Source):
You can put this solution on YOUR website!
Let x = current number of members in club
Let C = current cost per person
given:
C+=+200000%2Fx
C+-+2000+=+200000%2F%28x+%2B+5%29
-------------------------
By substitution:
200000%2Fx+-+2000+=+200000%2F%28x+%2B+5%29
Multiply both sides by x%2A%28x%2B5%29
200000%2A%28x+%2B+5%29+-+2000%2Ax%2A%28x%2B5%29+=++200000x
200000x+%2B+1000000+-+2000x%5E2+-+10000x+=+200000x
divide both sides by 1000
200x+%2B+1000+-+2x%5E2+-+10x+=+200x
2x%5E2+%2B+10x+-+1000+=+0
x%5E2+%2B+5x+-+500+-+0
x+=+%28-b+%2B-+sqrt%28+b%5E2-4%2Aa%2Ac+%29%29%2F%282%2Aa%29+
a+=+1
b+=+5
c+=+-500
x+=+%28-5+%2B-+sqrt%28+5%5E2-4%2A1%2A%28-500%29+%29%29%2F%282%2A1%29+
x+=+%28-5+%2B-+sqrt%28+25+%2B+2000+%29%29%2F2+
x+=+%28-5+%2B-+sqrt%282025%29%29%2F2
x+=+%28-5+%2B+45%29%2F2
x+=+20 (the negative root is invalid)
There are currently 20 members
check:
C+=+200000%2Fx
C+=+200000%2F20
C+=+10000
and
C+-+2000+=+200000%2F%28x+%2B+5%29
10000+-+2000+=+200000%2F%2820+%2B+5%29
8000+=+200000%2F25
8000+=+8000
OK

Answer by ptaylor(2198) About Me  (Show Source):
You can put this solution on YOUR website!
Let x=number of members currently in the club
($ understood)
cost per person=(200,000)/x
With five more people in the club the cost per person would be (200,000)/(x+5)
Now we are told that:
{(200,000)/x}-2000=(200,000)/(x+5) multiply each term by x(x+5)
(200,000)(x+5)-2000x(x+5)=200,000x get rid of parens
200,000x+1,000,000-2000x^2-10,000x=200,000x divide each term by 2000
100x+500-x^2-5x=100x subtract 100x from each side and then multiply each term by -1
x^2+5x-500=0---quadratic in standard form and it can be factored
(x+25)(x-20)=0
x=-25----------------------no good members are positive
x=20--------------------number of members currently in the club
CK
200,000/20=$10,000 per member
200,000/25=$8000 per member or $2000 less per member
Hope this helps---ptaylor