Question: Barry stands on his head for 10 minutes at a time, but then he must sit for 5 minutes before he can take another turn standing on his head. How many turns can Barry take standing on his head during a single 2-hour period? Think carefully first, then make a decision:
Each turn Barry takes standing on his head lasts for 10 + 5 = 15 minutes. 2 hours is 60 * 2 = 120 minutes. Barry can take 120 / 15 = 8 turns standing on his head over two hours. So the answer is 8.