posted by Taina on .
Rowing. Abby rows 10 km upstream and 10 km back in a total time of 3 hr. The speed of the river is 5km/h. Find Abby’s speed in still water.use five-step problem solving process
Don't know what the "five-step process" is, but here is how I would solve it ....
let her speed in still water be x km/h
time to go upstream = 10/(x-5)
time to go downstream = 10/(x+5)
solving : 10/(x-5) + 10/(x+5) = 3
10x + 50 + 10x - 50 = 3x^2 - 75
3x^2 - 20x - 75 = 0
x = (20 ± √1300)/6
= 9.34 km/h or a negative, which we reject
her still-water speed is 9.34 km/h