Question

Nikki used the calculations shown to determine whether a carton of 12 eggs or a carton of 18 eggs was the better buy.

A carton of 12 eggs cost $2.39 , and a carton of 18 eggs cost $3.39 .
Unit price of the 12 -egg carton = ($2.39)(12 eggs) = $28.68 per egg
Unit price of the 18 -egg carton = ($3.39)(18 eggs) = $61.02 per egg
The 12 -egg carton has the lower unit cost, so it is the better buy.

What was her first error?

Answer 1

She was supposed to DIVIDE the amount of money by the amount of eggs in the carton.

Explanation:

12 egg carton = $2.40, 1 egg = $2.40 ÷ 12 = 0.2c
18 egg carton = $3.40, 1 egg = $3.40 ÷ 18 = 0.188 (1.9)

The 18 egg carton was more affordable by about 1.22 cents. Nikki was supposed to divide the amount of money it was worth by the quantity in it.