SOLUTION: A survey crew took a trip up the river and back in 10 h. Going upstream they paddled at 4 km/h, but downstream they travelled at 12 km/h. How far upstream did the crew go?

Question 60884This question is from textbook Mathematics 11
: A survey crew took a trip up the river and back in 10 h. Going upstream they paddled at 4 km/h, but downstream they travelled at 12 km/h. How far upstream did the crew go? This question is from textbook Mathematics 11

Answer by uma(370) (Show Source): You can put this solution on YOUR website!
Let the distance travelled upstream = x km
Speed while going upstream = 4 km/h
So time taken = distance/speed
= (x/4)h
Speed while travelling downstream = 12 km/h
So time taken = distance/speed
= (x/12)h [distance upstream = distance downstream]
Total time taken = 12 h
==> x/4 + x/12 = 4
The LCD for the left side = 12
==> (3x + x)/12 = 4
==> 4x/12 = 4
multiplying both the sides by 12 we get..
==> 4x = 48
==> 4x/4 = 48/4
==> x = 12
So the distance upstream = 12 km
Good Luck!!!

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