# LT B week 4 - Speed against direction = (180-x) mph Now...

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Section 6.8: Exercises 36, 54, 64 36). Upstream downstream. Junior’s boat will go 15 miles per hour in still water. If he can go 12 miles downstream in the same amount of time as it takes to go 9 miles upstream, hen what is the speed of the current? Speed of current = x mph Speed when downstream = (15+x)mph Speed when upstream = (15-x)mph speed ce dis time tan = Distance Now according to the question both time are same so 143 . 2 7 15 21 45 45 21 135 180 12 9 12 180 9 135 ) 15 ( 12 15 ( 9 15 12 15 9 = = = = - = + - = + - = + + = - x x x x x x x x x x x x The speed of the current will be 2.143 mph #54). Big Plane. A six passenger plane cruises at 180 mph in calm air. If the plane flies 7 miles with the win in the same amount of time as it flies 5 miles against the wind, then what is the wind speed? Speed of wind = x mph Speed of plane in the direction of wind = (180 +x) mph

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Unformatted text preview: Speed against direction = (180-x) mph Now according to the question both time are same so 30 12 360 360 12 900 1260 7 5 5 900 7 1260 ) 180 ( 5 ) 180 ( 7 180 5 180 7 = = =-= + + =-+ =--= + x x x x x x x x x x x Speed of wind will be 30 mph #64). Filling a tank. A water tank has an inlet pipe and drain pipe. A full tank can be emptied in 30 minutes if the drain is opened and an empty tank can be filled in 45 minutes with the inlet pipe opened. If both pipes are accidentally opened when the tank is full, then how long will it take to empty the tank? min tan x k the empty to time = Sum of total work equals to 1 90 2 180 180 2 1 180 2 1 180 4 6 1 45 30 = = = = =-=-x x x x x x x x Tank will be empty in 90 minutes...
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## LT B week 4 - Speed against direction = (180-x) mph Now...

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