Candace is trying to decide whether to wear her old shoes or new high-tech shoes for a hike. The high-tech shoes will help Candace walk twice as fast, but they're not broken in yet, so she'll get 1 blister after every 2 hours she spends walking in them. Each blister slows Candance down by 2 miles per hour. If Candance walks 6 miles per hour in the old shoes and plans to hike for 4 hours, how many miles per hour can she go in the new shoes? Let's be accurate as possible.
Wearing the high - tech shoes, Candace can hike 6 mph * 2 = 12 mph for the first two hours. Then she gets one blister, so her speed drops to 12 mph - 2 mph = 10 mph for the next two hours of the hike. After that time Candace gets another blister, but 2 hours + 2 hours = 4 hours, so the hike is over and we don't care about her speed anymore. Candace spends an equal amount of time walking at 12 mph and 10 mph, so we can average the two speeds to find an overall speed of (12 mph + 10 mph) / 2 = 11 mph.
The answer: 11.