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Question 9:
Here's a question that may
not need x or y, but good algebra logic is
needed.
It comes from a Tri-County
Tech. book in South Carolina.
The
speed of a river is 5 mph. If a boat travels 98
miles downstream in the same time it takes to
travel 49 miles upstream, what is the speed of
the boat in still water?
Average distance travelled by
boat = (98 + 49) ÷ 2
(as in still water)
= 73.5 miles
Extra distance travelled
downstream = 98 - 73.5
= 24.5 miles
Total time of travelling
= extra distance ÷ speed
of river (mph) = 24.5 ÷ 5
= 4.9 hours.
Speed of boat in still
water
= Distance in still water
÷ time =
Click on the answer below you
believe is the correct
one,
and see if you are right.
'A' - 15
'B' -
16
'C'
-
17
'D' -
18.683
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