Question

If john makes a contribution to a charity fund at school, the average contribution size will increase by 50% reaching $75 per person. If there were 5 other contributions made before john's, what is the size of his donation?A. $100B. $150C. $200D. $250E. $450

Answer 1

Answer:

$Z= 75*6 -250=200$

So then the correct answer is B. $200.

Step-by-step explanation:

Notation

Let X be the average contribution size before John makes his contribution.

Let Y be the total contribution size before John makes his contribution.

Let Z be John's contribution.

We know that for this case $ 75 represent the original average amount before the contribution with 50% increase so we can set up the following equation in order to find the original average amount

$1.5 X = 75$

And solvong for X we got:

$X = \frac{75}{1.5}= 50$

Now we can find the total contribution before the donation with the following proportion:

$\frac{50}{1}= \frac{Y}{5}$

$Y = 250$

And then with the formula of average taking in count the 6 values we can find the size of donation Z like this:

$\frac{Y+Z}{6}= 75$

$\frac{250+Z}{6}= 75$

$Z= 75*6 -250=200$

So then the correct answer is B. $200.