SOLUTION: Hi Arthur was riding his bike to school at 12km per hour. When he was 2/3 of the w ay he got a flat tyre. His dad drove him the rest of the way at 48km per hour. What was his av

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Question 1185060: Hi
Arthur was riding his bike to school at 12km per hour. When he was 2/3 of the w ay he got a flat tyre. His dad drove him the rest of the way at 48km per hour. What was his average speed.
Thanks


Found 3 solutions by JBnovelwriter, josgarithmetic, greenestamps:
Answer by JBnovelwriter(34) About Me  (Show Source):
You can put this solution on YOUR website!
12%2B12%2B48=3x
72=3x
24=x
24km/hr = avg speed
12km/hr = a third
12km/hr = a third
48km/hr = a third
3/3
add them together divide by 3 to get average

Answer by josgarithmetic(39613) About Me  (Show Source):
You can put this solution on YOUR website!
Two different distance lengths described. First part may be 2L and last part may be L. 
               SPEEDS        TIME            DISTANCES

part1           12           (2L)/12            2L

part2           48           L/48               L

TOTALS                     (2L)/12+L/48        3L

Question is to find average speed of the whole trip.
%28totaldistance%29%2Ftotaltime

%283L%29%2F%28%282L%29%2F12%2BL%2F48%29

%283L%29%2F%288L%2F48%2BL%2F48%29

%283L%29%2F%28%289L%29%2F48%29

1%2F%283%2F48%29

48%2F3

highlight%2816%29

Answer by greenestamps(13195) About Me  (Show Source):
You can put this solution on YOUR website!


He rode twice as far on his bike, at a rate 1/4 the speed of the car. That means he spent 8 times as much time on his bike as in the car.

His average speed is then the weighted average of his two speeds:

%288%2812%29%2B1%2848%29%29%2F9+=+%2896%2B48%29%2F9+=+144%2F9+=+16

ANSWER: 16km/hr