Question

Judy can buy a 16oz box of cereal for $5.49 or a 20oz box for $5.99. Which is the better buy?

Answer 1

The 20 oz box is better value

Explanation:

The most straight forward way to do the comparison is to standardise the prices so that you have the cost for 20 oz in each case. That way you only need to convert one of them instead of both.
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`color(blue)("Consider 16oz box for $5.59")`

Write this in fractional form of a ratio

`("cost")/("quantity") -> ($5.49)/(16" oz")`

To change 16 into 20 multiply it by `20/16`

To maintain the correct proportion of the ratio we would need to multiply the top value in the same way. So we have:

`("cost")/("quantity") -> ($5.49)/(16" oz") -=($5.49xx(20/16))/(16xx(20/16)) = ($6.8625)/(20" oz")`
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So the 16 oz box is equivalent to $6.86 for 20 oz

Whilst the 20 oz box cost is $5.99

So the 20 oz box is better value