Question 252636
This is an RTD problem. Before we set up the rate x time = distance chart, we need to make sure all units are the same. Notice rate is in hrs and time is in minutes. Turn hours into minutes by using 60. Now for the RTD chart:
object . . . rate . . . time . . . distance
speed . . . .1 kpm . . .t - 5 . . . t - 5
sail . . . . r kpm . . .t . . . . . tr
total . . ..  . . . ..  120min . . .  .
We have two equations:
(i) t-5 = tr
(ii) t-5 + t = 120
we can solve equation (ii) for t as
t = 62.5 minutes
We can ow solve equation (i) for r as
r = (62.5-5)/62.5 ~ .92 kpm.
The rate of the fishing boat was ~.92kpm or 55.2kph.