SOLUTION: In the latest class reunion of HS '70, a certain number of succesful alumni promised to donate equally for a new school project amounting to $240 000.00. Four of them failed to pro

Question 1041185: In the latest class reunion of HS '70, a certain number of succesful alumni promised to donate equally for a new school project amounting to $240 000.00. Four of them failed to provide the certain amount of money. Hence, each of the remaining alumni had to pay $3 000.00 more to produce the sum. How many alumni had promised to pay originally?
Please state the solution! I really need to review this before our exams on Monday. Thanks alot.
Answer by ankor@dixie-net.com(22740) (Show Source): You can put this solution on YOUR website!
In the latest class reunion of HS '70, a certain number of successful alumni promised to donate equally for a new school project amounting to $240 000.00.
Four of them failed to provide the certain amount of money.
Hence, each of the remaining alumni had to pay $3 000.00 more to produce the sum.
How many alumni had promised to pay originally?
:
let a = the no. of alums that promised to pay
then
(a-4) = no. that actually paid
then
= amt that each originally agreed to pay
and
= amt that actually was paid
:
the equation, lets see if we can do this in "thousands of dollars"
- = 3
multiply by a(a-4)
a(a-4)* - a(a-4) = 3a(a-4)
cancel the denominators
240a - 240(a-4) = 3a^2 - 12a
240a - 240a + 960 = 3a^2 + 12a
combine on the right to form a quadratic equation
0 = 3a^2 - 12a - 960
simplify divide by 3
a^2 - 4a - 320 = 0
You can us the quadratic formula a=1; b=-4; c=-320 but this will factor to:
(a+16)(a-20) = 0
the positive solution is what we want here
a = 20 alums the original no. that promised to pay
:
:
let's see if this checks out, (16 alums actually paid).
- =
15 thousand - 12 thousand = 3 thousand

RELATED QUESTIONS
In the latest class reunion of HS '70, a certain number of succesful alumni promised to... (answered by MathTherapy)

In the latest class reunion oh HS batch 70, a certain number of successful alumni... (answered by ewatrrr)

There were p pupils in the junior class and they decided to spend D dollars on a school... (answered by TutorDelphia,MathTherapy)

Alyson opened a savings account with a deposit of $600. She withdrew $15 each day for the (answered by wuwei96815)

Math Question--- A certain number of persons promised to subscribe equally to a girft... (answered by stanbon,htmentor,MathTherapy)

A university is trying to select from a group of students who have volunteer to help out... (answered by edjones)

1. �/2 points Notes Problem 7-22 A food-packaging apparatus underfills 20% of the... (answered by solver91311)

Can you help me with this question please?: The hometown skates team was raising money... (answered by ikleyn)

Alyson opened a savings account with a deposit of $600. She withdrew $15 each day for the (answered by Theo)