math
posted by Anonymous on .
11. Runner A crosses the starting line of a marathon and runs at an average pace of 5.6 miles per hour. Half an hour later, Runner B crosses the starting line and runs at an average rate of 6.4 miles per hour. If the length of the marathon is 26.2 miles, which runner will finish ahead of the other? Explain

runner A runs 5.6 miles/hr so it will take him 4.68 hrs to run the marathon.
runner B runs 6.4 miles/hr so it will take 4.09 hrs to run the marathon
however runner B started half and hour later than runner A 4.68  .5 = 4.18
so runner B will finish the marathon .09hrs before runner A 
running time of faster runner = 26.2/6.4 or 4.125 hours or 4:7.5
running time of slower runner = 26.2/5.6 or 4.67857 hours or 4:40.7
remember the faster runner started 30 minutes later, so what do you think?