Question

A gallon of milks sells for $3.18 and a quart of milk sells for $0.76. Which item has the better unit price? Justify your answer using two different methods.

Answer 1

`Second\ price\ that\ is\ 1\ quart\ milk=\$0.76\ has\ better\ unit\ price`

Explanation:

Use gallon unit:

First Price:

`1\ gallon\ milk=\$3.18\\\\`

Second Price:

`4\ quart=1\ gallon\\\\1\ quart\milk=\$0.76\\\\4\ quart\ milk=4* 0.76=\$3.04\\\\\Rightarrow 1\ gallon\ milk=\$3.04`

`1\ gallon\ at\ first\ price\ is\ greater\ than\ the\ rate\ of\ 1\ gallon\ at\ second\ price\\\\Hence\ 1\ quart=\$0.76\ has\ the\ better\ unit\ price.`

Second Method: Use Quart Unit:

First Price:

`1\ gallon=4\ quart\\\\1\ gallon\ milk=\$3.18\\\\4\ quart\ milk=\$3.18\\\\1\ quart\ milk=(3.18)/(4)=\$0.795`

Second Price:

`1\ quart\ milk=\$0.76`

`Second\ price\ that\ is\ 1\ quart\ milk=\$0.76\ has\ better\ unit\ price`