Step-by-step explanation:
Distance = rate × time
If b is the speed of the boat in still water, and c is the speed of the current, then:
60 = (b + c) × 4
35 = (b − c) × 3.5
Simplifying:
15 = b + c
10 = b − c
Add the equations together:
25 = 2b
b = 12.5
Plug into either equation to find c:
c = 2.5
The speed of the boat is 12.5 km/h, and the speed of the current is 2.5 km/h.
Answer: The speed of the boat in still water is 12.5 mph and the speed of the current is 2.5 mph
Step-by-step explanation:
Let x represent the speed of the motorboat in still water.
Let y represent the speed of the current.
The motorboat travels 60 km in 4 hours with the current. This means that the total speed of the motor boat would be (x + y) km/h.
Distance = speed × time
Distance travelled by the motorboat with the current is
60 = 4(x + y)
Dividing through by 4, it becomes
15 = x + y-- - - - - - - - - - -1
The motorboat travels 35 km in 3.5 hours against the current. This means that the total speed of the motorboat would be (x - y) km/h.
Distance travelled by the motorboat with the current is
35 = 3.5(x - y)
Dividing through by 4, it becomes
10 = x - y-- - - - - - - - - - -2
Adding equation 1 to equation 2, it becomes
25 = 2x
x = 25/2 = 12.5 mph
Substituting x = 12.5 mph into equation 1, it becomes
15 = 12.5 + y
y = 15 - 12.5
y = 2.5 mph
