Answer: if there had been no current, the rate would have been 4 km/hr.
The rate of the current is 1.5km/hr
Step-by-step explanation:
Let x represent the speed of the boat in still water.
Let y represent the speed of the current.
Impeded by the current the outing club took 4 hours and 24 minutes(4 + 24/60 = 4.4 hours) to paddle 11 km up the exeter river to their campsite last weekend. This means that the total speed with which they travelled is (x - y) km/h
Distance = speed × time. Therefore
11 = 4.4(x - y)
Dividing through by 4.4, it becomes
2.5 = x - y - - - - - - - - - - -1
The next day the same current was with them and it took only 2 hours to make the return trip to campus. This means that the total speed with which they travelled is (x + y) km/h. The distance travelled is
11 = 2(x + y)
Dividing through by 2, it becomes
5.5 = x + y - - - - - - - - - - -2
Adding equation 1 to equation 2, it becomes
8 = 2x
x = 8/2 = 4
Substituting x = 4 into equation 1, it becomes
2.5 = 4 - y
y = 4 - 2.5
y = 1.5
