Question

Two boats start together and race across a 74-km-wide lake and back. Boat A goes across at 74 km/h and returns at 74 km/h. Boat B goes across at 37 km/h, and its crew, realizing how far behind it is getting, returns at 111 km/h. Turn around times are negligible, and the boat that completes the round trip first wins..
a) Which boat wins? (or is it a tie?)
b) By how much?....km
c) What is the average velocity of the winning boat? ....km/h

Answer 1

Answer:

74 Km/h

Explanation:

For boat A:

1 = 2l/v_1

  =2×74/74  h

  =2h

where = 74 wide of the lake, 1- speed of boat A

For boat B:

2 = l/v_21   + l/v_22    

    = 74/37  + 74/111 ℎ

    = 2.66 ℎ

where v_21= 37 /ℎ and v_22 = 111 /ℎ speeds of boat B

boat A completes the round trip first. The difference of times equals:

                                                ∆ = 2 − 1

                                                     =2.66 ℎ − 2ℎ

                                                     =0.66 ℎ or 40 n

boat A, ∆ = 40 n

c) Average speed for boat A equals:

                                               V = 2 /1

                                                     =148/2 Km/h

                                                     =74 Km/h