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1.ImaginethatyouhavetrainedyourSt.Bernard,Bernie,tocarryaboxofthree8mmtapesinsteaImaginethatyouhavetrainedyourSt.Bernard,Bernie,tocarryaboxofthree8mmtapesinsteadofaflaskofbrandy.Thesetapeseachcontain7gigabytes.Th

题目详情
1.Imagine that you have trained your St.Bernard,Bernie,to carry a box of three 8mm tapes instea
Imagine that you have trained your St.Bernard,Bernie,to carry a box of three 8mm tapes instead of a flask of brandy.These tapes each contain 7 gigabytes.The dog can travel to your side,wherever you may be,at 18 km/hour.For what range of distances does Bernie have a higher data rate than a transmission link whose data rate (excluding overhead) is 150 Mbps?
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答案和解析
Assuming there is no need (after the dog reaches his destination) for the information on the tape to be transferred to another storage device, all you need to do is convert 150 mbps into similar units, then find out the ratio and then the distance.
150 mbps = 150 x 360 mb/hr, = 54000 mb/hr = 54000/1024 gb/hr = 52.73 gb/hr.
The dog has to make a two-way trip every time, so if the distance is 9 km, then his rate is 21 GB/hour. The ratio between these two rates can then be used to calculate the maximum distance:
52.73/21 = 9 km/ distance, so distance = 3.58 km. The distance range is [0, 3.58).
First of all, the dog must make 2-way trips. Each time, he can carry 21 GB of information. Set a variable x as time, then