Problem-Solving and Data Analysis practice question

Answer: C. 25%

Percent change = (change / original) × 100 = (10 / 40) × 100 = 25%. Divide by the ORIGINAL value (40), not the new one — that's the classic trap (choice B).

Why the other answers are wrong

A. 10%

$10 is the raw dollar increase, not the percent — you still need to divide by the original price: 10 ÷ 40 = 25%.

B. 20%

You divided the $10 change by the new price ($50) instead of the original ($40). Percent change always uses the starting value as the denominator.

D. 50%

50% would mean the stock went from $40 to $60. The increase is $10 on a $40 base, so 10 ÷ 40 = 25%.

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