### Brain Teasers

# Pizza Discount

The 10" pizza sells for $3.99 at my favorite pizza store. The store claims they have a great deal on the large 12" pizza, which is specially priced at $ 4.31. What is the per cent discount the store is offering?

### Answer

25The small pizza has a diameter of 10" and therefore an area proportional to 10^2 = 100.

The large pizza has a diameter of 12" and therefore an area proportional to 12^2 = 144.

If the pizzas are priced according to their areas, then,

Price of large pizza / Price of small

pizza = (12 / 10)^2 = 1.44

Normal price of large pizza = 1.44 x $3.99 = $5.75.

Thus, discount on large pizza = [1 - ($4.31 / $5.75)] x 100 = 25%.

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## Comments

This is just school house number crunching.

Are these pizzas round or are they square?

They are round.

Man, that is hard!!!!! Mainly because i am not in high school yet. I am in 6th grade. High school next year. As of 2010.

im a sophomore and did not get that and i have a 80 in math but but im in algebra idk its confusing

small correction needed: area of a circle is pi r^2, hence, its is not 10^2 and 12^2 as those are diameters, the correct should be to take radius: so it should be 5^2 and 6^2. There will be no change in the final answer though, as the ratios will remain consistent nonetheless.

Thanks addspras! I will fix that.

A tricky one but simple.

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