Is buying 355ml of something for $53.64 cheaper than buying 250ml of the same thing for $49.07?
Thanks to anyone who answers :)

Question

Is buying 355ml of something for $53.64 cheaper than buying 250ml of the same thing for $49.07?

Thanks to anyone who answers :)

Answer

Actually, buying the bigger product (355ml) is cheaper because you get more product for your money. The 250ml should only cost $37.77 if you paid the same 1ml price for it, but since they charge $49.07 you are paying about $8 more for the same product.

Answer

As the two preceding answers suggest, this appears to be rather a philosophical than a mathematics question. Even teachers of mathematics tend to feel obliged to educate their students in the spirit of our beloved capitalist society system (to mold them into valuable members of society), which boils down to:
"Buy things you don't need from money you don't have to impress people you don't like!". Truth be told, it wouldn't stand to reason If you need, say, 220ml of the substance just once, to buy 355ml merely because it's cheaper per ml. 

But let's assume for the time being that the question is just a harmless exercise. You won't have to have received the major orders of maths so as to wrap your head around the Rule of Three:

You've got two Prices P1, P2 and two Package Sizes S1, S2 (both in ml, so no unit conversion is required) of the same stuff (otherwise it wouldn't be comparable in the first place). Let's compare the prices per base unit (ml):

(?: ($53.64 / 355ml) < ($49.07 / 250ml))

(?: ($0.151 / ml)  < ($0.196 /ml)) returns TRUE. 

Thus, the package size with 355ml is cheaper per ml.

Is buying 355ml of something for $53.64 cheaper than buying 250ml of the same thing for $49.07?

Responses (3)