Question 1115995
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There are all kinds of alternatives to the standard algebraic solution method shown by the other tutor.  Of course, that method is fine; but here are a couple of alternatives that you might try, if getting to the answer faster is what you want.<br>
(1) logical reasoning...<br>
If he traveled all 6 hours at 60 mph, he would only have gone 360 miles -- not 380.  To get those extra 20 miles going 10 mph faster, he has to drive at the higher speed for 20/10 = 2 hours.  So he drove at 60 mph for 4 hours and 70 mph for 2 hours.<br>
(2) finding the ratio of times spent at the two speeds by comparing the average speed for the whole trip to the two different speeds...<br>
His average speed was 63 1/3 mph, which is one-third of the way from 60 to 70.  That means he spent one-third of his time at the higher speed.  So he spent 2 hours at 70 mph, which means he spent 4 hours at 60 mph.