Mobius is the fastest mule in Italy. She can run at a top speed of 13 miles per hour when she is without any load to carry, and she can travel at 11 miles per hour as her top speed when she carries a typical load. If she travels the 143 miles from Florence, Italy to Rome, Italy at top speed while carrying a typical load, then returns to Florence at her usual top speed without carrying a load, how long, in hours, will the trip take if she takes two 30-minute rest stops during each half of the trip? Let's answer step by step:
30 minutes is 30 / 60 = 0.5 hours. Two 30 - minute rest stops take 0.5 * 2 - 1 hour. If she takes two rest stops per each half of the journey, then she takes 2 * 1 = 2 hours in rest time. With a load, at her top speed, she can travel 143 miles in 143 / 11 = 13 hours. Without a load, at her top speed, she can travel 143 miles in 143 / 13 = 11 hours. Thus, the round trip will take 13 + 11 + 2 = 26 hours. The answer: 26.