Christopher J. answered • 05/12/20

Berkeley Grad Math Tutor (algebra to calculus)

Jason:

Remember that velocity*time=distance or v*t=d

let's call v_{u }the upstream velocity. we know v_{d}, the downstream velocity is 25% faster than the upstream velocity. This means v_{d}=1.25*v_{u}

we also know d=2. Time to row upstream is t_{u}=d/v_{u}=2/v_{u}

Time to row downstream is t_{d}=d/v_{d}=d/(1.25*v_{u})=2/(1.25*v_{u})=1.6/v_{u}

Total time is t_{u }+ t_{d} = 2/v_{u }+ 1.6/v_{u}

if v_{u}=20, you can plug that value in to find the total time spent rowing