问问?没看懂咋算出来的答案?Question #4:A cyclist bikes from town A to town B and back to town A in 3 hours.He bikes from A to B at a speed of 15 miles/hour,while his return speed is 10 miles/hour.What is the distance between the 2 towns?(a
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![问问?没看懂咋算出来的答案?Question #4:A cyclist bikes from town A to town B and back to town A in 3 hours.He bikes from A to B at a speed of 15 miles/hour,while his return speed is 10 miles/hour.What is the distance between the 2 towns?(a](/uploads/image/z/7613114-50-4.jpg?t=%E9%97%AE%E9%97%AE%3F%E6%B2%A1%E7%9C%8B%E6%87%82%E5%92%8B%E7%AE%97%E5%87%BA%E6%9D%A5%E7%9A%84%E7%AD%94%E6%A1%88%3FQuestion+%234%3AA+cyclist+bikes+from+town+A+to+town+B+and+back+to+town+A+in+3+hours.He+bikes+from+A+to+B+at+a+speed+of+15+miles%2Fhour%2Cwhile+his+return+speed+is+10+miles%2Fhour.What+is+the+distance+between+the+2+towns%3F%28a)
问问?没看懂咋算出来的答案?Question #4:A cyclist bikes from town A to town B and back to town A in 3 hours.He bikes from A to B at a speed of 15 miles/hour,while his return speed is 10 miles/hour.What is the distance between the 2 towns?(a
问问?没看懂咋算出来的答案?
Question #4:A cyclist bikes from town A to town B and back to town A in 3 hours.He bikes from A to B at a speed of 15 miles/hour,while his return speed is 10 miles/hour.What is the distance between the 2 towns?
(a) 18 miles
(b) 15 miles
(c) 12 miles
(d) 10 miles
(e) 11 miles
Answer:The total time t = tAB + tBA = dAB/(15 miles/hour) + dAB/(10 miles/hour) = dAB/(6 miles/hour).
dAB = dAB/(6 miles/hour) · 3 hours = 18 miles.
(a) is the correct answer.
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问问?没看懂咋算出来的答案?Question #4:A cyclist bikes from town A to town B and back to town A in 3 hours.He bikes from A to B at a speed of 15 miles/hour,while his return speed is 10 miles/hour.What is the distance between the 2 towns?(a
a
假设A离B距离为S,从A到B花了a小时,B到A花了b小时
设三个方程:15a=10b=2s 15a+10b=2s a+b=3 得出S=18