Pizza Discount
Math brain teasers require computations to solve.
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
25
The 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
stil
May 03, 2010
 This is just school house number crunching. 
comeon
May 04, 2010
 Are these pizzas round or are they square? 
Yazmeen
May 04, 2010
 They are round. 
bbcoolbeans7
May 04, 2010
 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. 
BRAINIACGURL
May 04, 2010
 im a sophomore and did not get that and i have a 80 in math but but im in algebra idk its confusing 
addspras
May 05, 2010
 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. 
Yazmeen
May 05, 2010
 Thanks addspras! I will fix that. 
RRAMMOHAN
Oct 27, 2012
 A tricky one but simple. 
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