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LostInParadise's avatar

Which is the better way of framing the solution to this simple math problem?

Asked by LostInParadise (25653points) 4 days ago

I was thinking of using this problem for tutoring. I can see two ways of answering it, and I can see advantages to each approach.

Problem
A store buys 10 widgets at $2 each and sells 8 of them for $3 each. What is the store’s profit?

Method 1. Total cost is 10 x $2 = $20. Revenue from selling 8 is 8 x $3 = $24. Profit = $24 – $20 = $4.

Method 2 – Profit from widgets sold is $1 per widget sold. 8 widgets sold gives profit of 8 x $1 = $8. Cost of 2 unsold widgets is 2 x $2 = $4. $8 – $4 = $4.

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6 Answers

josie's avatar

I like Method 1
Where does it say in the problem that profit is $1

LuckyGuy's avatar

I used Method 1 as I was reading the problem.

LostInParadise's avatar

What if we have 2 widgets bought for $1, 3 for $2 and 5 for $3, all sold for $5 each? Doesn’t it become easier to add up the profit on each group? Profit = 2 x $4 + 3 x $3 + 5 x $2 = $27.

seawulf575's avatar

I’d go with Method 1. It’s more straightforward and fewer math evolutions.

LuckyGuy's avatar

In your later example in my head I thought 2 x $1 + 3 x $2 + 5 x $3 = $2 + $6 + $15 = $23 spent
and 2 + 3 + 5 = 10, x $5 = $50 received. = 50 – 23 = 27 profit.

Dutchess_III's avatar

@josie the cost to buy them is $2 each. They sell them for $3 each. That’s your $1 profit.

I like method 1 too.

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