Best Answer

Let s = unknown speed in still water in units of miles per hour. The downstream speed will then be s + 4 and the upstream speed s - 4. In an equal time t in units of hours, t(s+4) = 40 and t(s-4) = 24. Multiplying out the parenthetical expressions yields ts + 4t = 40 and ts - 4t = 24. Subtracting the second of these equations from the first gives 8t = 16, or t = 2 hours. Therefore, ts +4t = 40, by substituting 2 for t becomes:

2s + 8 = 40, or 2s = 40 - 8 = 32, or s = 16 miles per hour.

Q: A river has a current of 4 mph find the speed of simons boat in still water if it goes 40 miles downstream in the same time as 24 miles upstream?

Write your answer...

Submit

Still have questions?

Continue Learning about Math & Arithmetic

2 Miles An Hour.

The current speed is about 4 miles per hour.

assume river velocity = X mph boat velocity = 20 mph time to go 6 miles downstream = T1 time to go 3 miles upstream = T2 distance = time * velocity downstream: 6 mi = T1 * (boat velocity + river velocity) upstream: 3 mi = T2 * (boat velocity - river velocity) 6 = T1 * ( 20 + X ) 3 = T2 * ( 20 - X ) T1 * ( 20 + X ) = 2 * ( T2 * ( 20 - X ) ) since T1 = T2 then 20 + X = 40 - 2X 3X = 20 X = 6.67 thus, river velocity is 6.67mph

The average speed downstream is 40 ÷ 4 = 10 mph. However, it would seem that insufficient information has been supplied to enable a satisfactory answer to this question to be provided.

2 miles per second upstream relative to the river bank.Note: This is quite a scenario, even for experienced rapids-shooters.That river is flowing at 28,800 miles per hour, and the guy is paddlinghis kayak through the water at 36,000 miles per hour. The whole sceneis definitely poised to launch itself into solar orbit.

Related questions

The current is approximately 4 mph.

2 Miles An Hour.

Let boat speed = X and current speed = Y Downstream speed = boat speed plus current speed = X + Y Upstream speed = boat speed minus current speed = X -Y Downstream speed = 2 miles divided by 3 minutes = 2/3 miles per minute Upstream speed = 2 miles divided by 15 minutes = 2/15 miles per minute X + Y = 2/3 X - Y = 2/15 add equations 2X = 2/3 + 2/15 = 10/15 + 2/15 = 12/15 = 4/5 divide by 2 X = 4/10 = 2/5 use second equation and find Y as X -Y = 2/15 2/5 - Y = 2/15 6/15 - Y = 2/15 Y = 4/15 = current speed = 0.266 miles per minute

Boats speed = 24 miles per hour.Current speed = 4 miles per hour.

The gradient of the River Amazon is very low. It is 1,000 miles or 1,610 kilometers upstream, and 100 feet or 30 meters downstream.

8 MPH

Speed upstream(S.u) = 20/5 => 4miles/hr Speed downstream(S.d) = 10/2 => 5miles/hr Speed of man in still water(speed of boat in still water)= 1/2 * (S.u + S.d) = 0.5 * (4 + 5) = 0.5 *9 = 4.5miles/hr The speed of man in still water is 4.5 miles/hr

Her average speed is 1.6 miles per hour. Average speed is total distance covered by total time taken to do it. She swims 4 miles upstream, and at 1 mph, it takes 4 hours. She comes back downstream at 4 mph and so she covers the 4 miles in 1 hour. Her total mileage is 8 miles. It takes 4 + 1 hours or 5 hours to cover it. The 8 miles divided by 5 hours is 1 3/5 miles per hour, or 1.6 mph for an average speed.

The current speed is about 4 miles per hour.

Since the distance downstream (with the current) equals the distance upstream (against the current), and if we: Let B stand for the speed (rate in mph) of the boat in still water, and using the formula rate X time = distance, the equation will be: (B+7) x 3 = (B-7) x 5 3B + 21 = 5B - 35 56 = 2B B = 28 mph Traveling downstream, the current will cause the boat to go faster so the 7 mph current is added to the boat's still water speed. Traveling upsteam the current slows or decreases the boat's rate so the current's speed is subtracted from the boat's still water speed.

assume river velocity = X mph boat velocity = 20 mph time to go 6 miles downstream = T1 time to go 3 miles upstream = T2 distance = time * velocity downstream: 6 mi = T1 * (boat velocity + river velocity) upstream: 3 mi = T2 * (boat velocity - river velocity) 6 = T1 * ( 20 + X ) 3 = T2 * ( 20 - X ) T1 * ( 20 + X ) = 2 * ( T2 * ( 20 - X ) ) since T1 = T2 then 20 + X = 40 - 2X 3X = 20 X = 6.67 thus, river velocity is 6.67mph

salmon