New packaging for fruit snacks contains 10% less weight than the original packaging. If the new package costs 15% more than the original package, by what fraction did the unit price increase? Express your answer as a common fraction.

5/18

Step-by-step explanation:

Let's say the original packaging was 1 lb of packaging for $1.

The cost was $1/lb.

Then the weight went down by 10% and the price went up by 15%.

Now 0.9 lb of packaging cost $1.15.

The new unit cost is $1.15/(0.9 lb)

The difference is

$1.15/(0.9 lb) - $1/lb =

= $1.15/(0.9 lb) - $0.9/(0.9 lb)

= $0.25/(0.9 lb)

=$25/(90 lb) = $5/(18 lb)

The price went up by 5/18.