Marissa is hiking a 12-mile trail. She took 1 hour to walk the first 4 miles, then another hour to walk the next two miles. If she wants her average speed to be 4 miles per hour, what speed (in miles per hour) does she need to walk the remaining distance?
First figure out how many hours it takes to hike a 12-mile trail at 4 mph by dividing the distance by the speed: 12 miles / 4 mph = <<12/4=3>>3 hours
Next subtract the time Marissa already spent walking to find out how much time she has left: 3 hours - 1 hour - 1 hour = <<3-1-1=1>>1 hour
Now figure out how much distance she has left by subtracting the distance she already traveled from the total distance: 12 miles - 4 miles - 2 miles = <<12-4-2=6>>6 miles
Now divide the remaining distance by the remaining time to find out how fast in miles per hour Marissa has to travel: 6 miles / 1 hour = <<6/1=6>>6 mph
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