AlexTheTrainer
Yvonne invited x people for dinner and plans to buy a pizza with a diameter of 14 inches. When she discovers that x + z people will be coming to dinner, how much greater in diameter does the pizza need to be, in terms of x and z, so that each person receives the same amount of pizza that Yvonne had originally planned?
(A) \(\frac{49𝜋x}{z}\)
(B) \(\frac{14\sqrt{xz}}{x}\)
(C) \(\frac{49𝜋z}{x}\)
(D) \(\frac{7\sqrt{xz}}{z}\)
(E) \(\frac{z}{7\pi x}\)
The distribution would always be on the area.
So, area =\(\pi r^2=49\pi\), and each of x would get \(\frac{49\pi }{x}\).
If z join in to make the new strength x+z, the requirement of quantity of pizza such that each gets \(\frac{49\pi }{x}\) = \(\frac{49z\pi }{x}\)
Thus the area =\(\pi r^2=\) \(\frac{49z\pi }{x}\)
\(r^2=\frac{49z}{x}......r=7*\frac{\sqrt{z}}{\sqrt{x}}\)= \(\frac{7\sqrt{xz}}{x}\)
The diameter or 2r would be \(\frac{14\sqrt{xz}}{x}\)
B
It would be better to reword the question to ‘
what should be the diameter of the pizza now’ from
how much greater in diameter does the pizza need to be as the wordings now could suggest we are comparing the two diameters and looking at the increase in diameter.
Writers (like me) need editors because we have blindspots when it comes to our own material. That being said, I am 98% certain that the answer you selected was indeed the additional diameter and not the new diameter. That is, I’m quite certain the question was phrased properly and that you answered it properly.
Would you mind triple checking your work? Very difficult to get rid of a blind spot and you might be right.