SOLUTION: Bob walked a total of 2.5 miles on a treadmill He walked 2 mikes per hour for one third of the time and 4 miles per hour for two third of the time. What amount of time did he wal

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Question 971576: Bob walked a total of 2.5 miles on a treadmill He walked 2 mikes per hour for one third of the time and 4 miles per hour for two third of the time. What amount of time did he walk on treadmill
Answer by josmiceli(19441) About Me  (Show Source):
You can put this solution on YOUR website!
Let +d+ = distance Bob walked at +2+ mi/hr
+2.5+-+d+ = distance he walked at +4+ mi/hr
Let +t+ = total time he walked on treadmill
---------------------------------------------
Walking at 2 mi/hr:
(1) +d+=+2%2A%28+1%2F3+%29%2At+
Walking at 4 mi/hr
(2) +2.5+-+d+=+4%2A%28+2%2F3+%29%2At+
---------------------------
Substitute (1) into (2)
(2) +2.5+-+2%2A%281%2F3%29%2At+=+4%2A%28+2%2F3+%29%2At+
(2) +%28+8%2F3+%29%2At+%2B+%28+2%2F3+%29%2At+=+2.5+
(2) +%28+10%2F3+%29%2At+=+10%2F4+
(2) +t%2F3+=+1%2F4+
(2) +t+=+3%2F4+
He was on the treadmill for 3/4 hr or 45 min
check:
(1) +d+=+2%2A%28+1%2F3+%29%2At+
(1) +d+=+2%2A%28+1%2F3+%29%2A%283%2F4%29+
(1) +d+=+1%2F2+ mi
and
(2) +2.5+-+d+=+4%2A%28+2%2F3+%29%2At+
(2) +2.5+-+1%2F2+=+4%2A%28+2%2F3+%29%2At+
(2) +2+=+4%2A%28+2%2F3+%29%2At+
(2) +6+=+8t+
(2) +t+=+3%2F4+ hr
OK