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 is right, however her explanation is wrong.

In order to find the unit price, you need to divide the amount by the cost.

You will then see that 12 divided by 2.39 < 18 divided by 3.39.

The smaller unit price is obviously the better buy.

Explanation:

Answer 2

Given :

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.

To Find :

What was her first error.

Solution :

Her first error is to find Unit price of egg in each carton.

To find, unit price we should divide total amount by number of units :

Unit price for carton of 12 eggs, $ (2.39)/12 = $0.199 .

Hence, this is the required solution.