QuantumWonder wrote:
hugebigmac wrote:
draw two graphs. one for 20x^2 and one for 300x.
They will met at 15. After 15, 20x^2 will always larger than 300x.
The largest gap lies between 7 and 8. since there can only be integer number of guest, put 7 and 8 into the equation. we get 1120, which is below 1200.
Answer is E.
Why 20x^2 and not 20x? I am not following.
Can anyone give an alternative solution as well?
Approach 1:Each person will donate = \((300 - 20x)\)
Total Donation = \((300 - 20x)\) x \(x\) = \($1200\)
i.e. \(20x^2 -300x + 1200 = 0\)
Upon solving, you will get Imaginary roots, Hence you cannot raise the desired amount of \($1200\)
So, option E
Approach 2:You can simply plug in the option choices, and you will notice even when \(x = 8\), the raised amount is \($1120\)
So we can go with option E