Rina03id
Answered

Domino can eat 12-inch pizza for 20 minutes. How long does it take for him to eat a 18-inch pizza? Note: Number 1 question in difficult for grade 7 students in the finals here at Rizal High School in Caniogan, Pasig City. The judges said that the answer isn't 30 minutes. No one got the correct answer so please...

Sagot :

They said the answer was 45 minutes. According to them, you must find the area of the pizza. So, it seems like the 12 in. and 18 in. is the radius. Lol, I even saw that in a mini book that have tricky problems like that. It also seems that you only needed the explanation why 30 minutes isn't the answer ☺ So, I guess I won't do the equation ;)
Find the area of each pizza:

Pizza A = 12-inch diameter
Radius: 6 inches
Area = π r²
         = 3.14 (6 inches)²
         = 3.14 (36 inches²)
         = 113.04 inches²
Consumed in: 20 minutes

Pizza B = 18-inch diameter
Radius =   9 inches
Area = 3.14 (9 inches)²
         = 3.14 (81 inches²)
         = 254.04 inches²
Consumed in: x minutes

Equation:
Let the number of minutes it takes to finish 18-inch pizza:

[tex] \frac{113.04}{20} = \frac{254.34}{x} [/tex]

113.04 (x) = (20) (254.34)

[tex] \frac{113.04x}{113.04} = \frac{5,086.80}{113.04} [/tex]

x = 45

ANSWER:  It takes 45 minutes to finish an 18-inch diameter pizza.