Bundle prices without unit prices: when can your child infer the individual prices?
By Erik Nilsen · Kroni2 min read
Two bundle prices can reveal a unit price if the bundles use identical prices per component without special discounts. Make that assumption explicit. Without it, your child cannot infer what individual items actually cost.
Subtract the shared contents
In a hypothetical shop game, two pens and one notebook cost 26 units. Two pens and two notebooks cost 42. The game rule permits individual purchases at the same fixed unit prices, without discounts or extras. Everything is invented.
The second bundle contains exactly one additional book. The difference is 42 − 26 = 16, so one book costs 16 units under this rule.
The first bundle then leaves 26 − 16 = 10 for two pens. One pen therefore costs 10 / 2 = 5. Check with 2 × 5 + 16 = 26 and 2 × 5 + 2 × 16 = 42.
One pen and one book consequently cost 5 + 16 = 21. A budget of 20 falls short by 1. Your child cannot select a bundle price as though it automatically covers another quantity.
Check when the inference is valid
A practical snag is applying the same method to real discounted kits. If the two-book bundle has its own discount, a price difference of 16 does not necessarily establish an individual book price of 16. The calculation depends on identical fixed component prices.
Ask your child to identify shared contents and the additional item. Then check the individual price before an actual purchase. A calculated suggestion is not a seller's confirmed price.
Ask your family: “Do we know the parts use identical unit prices, or are we comparing separate bundle offers?”
Carry the calculation into your family agreement
Kroni can keep track of your child's virtual balance. The app does not transfer money, so any actual purchase is paid for outside it. Agree on what you will record, then check the amount with your child afterwards. Do not deduct a possible cost as though the purchase had already happened. Read about allowance in Kroni.
