word problem regarding calories

Question

A 6 inch personal pizza has 580 calories, with 240 of those from fat. A 12 inch pizza is cut into 8 slices. Estimate the number of calories in one slice of a 12 inch pizza.

Answer 1

The 6-inch pizza is circular and has a diameter of 6 inches.  It has a radius of 3 inches and an area A₆ = πr² = 9π.

 

The 12-inch pizza is circular and has a diameter of 12 inches.  It has a radius of 6 inches and an area A₁₂= πr² = 36π.

 

Note that we are assuming circular pizzas and not distinguishing calories in the crust area.

 

The 12-inch pizza has 4 times as many calories as the 6-inch pizza (36π=4*9π).  So, it has 4*580=2320 calories.  1/8th of that is 290.

 

Now, since the problem said "estimate," use 600 as a "nice" number near 580, multiply it by 4 to get 2400, take 1/8th to get 300.  That's a very close, easy, first estimate.

Answer 2

The 12-inch pizza would have twice as many calories as the

6-inch one: 1160. If you divide the calories by the number

of inches (1160/12), there are approximately 96.66 calories

per 1-inch slice. Since the pizza is cut into 8 slices, their

measurement would = 1 1/2 inches per slice, so the

calories would be 96.66 x 1 1/2, which would = 145 calories per slice.

 

Go Get Your "A"

Answer 3

6 inches = 580 calories

1 inch  = 96.66 calories

 

12 inch pizza = 8 slices

1.5 inches = 1 slice

 

1 slice = 1.5(96.66) = 145 calories