Question 160640
Jones can run around a 400-meter track in 65 seconds. How long does Smith take
 to run the 400 meters if he meets Jones in 35 seconds after they start together
 in a race around the track in opposite directions?
:
When they meet, they will have traveled a total of 400 meters in 35 seconds
:
Find Jone's speed in meters/sec: {{{400/65}}} = 6.154 m/sec
:
Let s = Smith's speed in m/sec
:
Write a dist equation; Dist = time * speed
:
35s + 35(6.154) = 400
:
35s + 215.39 = 400
:
35s = 400 - 215.39
:
35s = 184.61
s = {{{184.61/35}}}
s = 5.275 m/sec is Smith's speed
:
Find time for Smith to run 400 m: 
{{{400/5.275}}} = 75.83 sec to run 400 m
:
:
Check solution: 
35 * 5.275 = 184.625 m
35 * 6.154 = 215.39
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Total dist = 400.0