At the opening of a trading day at a certain stock exchange, the price per share of stock K was $10. If the price per share of stock K was $15 at the closing of the day, what was the percent increase in the price per share of stock K for that day? Options.
A) 1.4 % B) 50 % C) 11.1 % D) 12.5 % E) 23.6 %

Rationale: opening = 10 closing = 15 rise in price = 5 so , percent increase = 5 / 10 * 100 = 50 % answer : b
Answer: B