It took a crew 2 h 6 min to row 7 km upstream and back again. If the rate of flow of the stream was 8 km/h, what was the rowing speed of....?

It took a crew 2 h 6 min to row 7 km upstream and back again. If the rate of flow of the stream was 8 km/h, what was the rowing speed of the crew in still water?

1 Answer

Relevance
  • 1 month ago

    time = distance/ speed

    Time against current + time with current = 2hr 6 min = 2.1hr

    7/(s - 8) + 7/(s + 8) = 2.1

    Multiply both sides by (s - 8)(s + 8)

    7(s + 8) + 7(s - 8) = 2.1(s - 8)(s + 8)

    14s = 2.1(s² - 64)

    14s = 2.1s²  - 134.4

    2.1s² - 14s -134.4 = 0

    Solve using quadratic equation (work not shown)

    s = {-5.333, 12}

    The speed is positive 

    12 k/hr <–––––

    • nadine1 month agoReport

      Thank You

    • Commenter avatarLog in to reply to the answers
Still have questions? Get answers by asking now.