Final answer:
To verify the selling price with a 40% markup on an item that costs $2.50, calculate the markup amount ($1.00) and add it to the cost price. The correct selling price is $3.50.
Step-by-step explanation:
To determine if your friend calculated the selling price correctly with a 40% markup, we first calculate the markup amount by taking 40% of the store's cost price of $2.50. To find 40% of $2.50, we multiply the cost price by the markup percentage (expressed as a decimal).
Markup amount = $2.50 × 0.40 = $1.00.
Next, we add the markup amount to the original cost price to find the selling price:
Selling price = Cost price + Markup amount
Selling price = $2.50 + $1.00 = $3.50.
Therefore, if your friend found the selling price to be $3.50, then they are correct.