Answer: the rate of the boat in calm water is 9 mph and the rate of the current is 7 mph
Step-by-step explanation:
Let x represent the rate of the boat in calm water.
Let y represent the rate of the current.
A boat goes 32 miles downstream in two hours. Assuming that it travelled in the direction of the current, its total speed would be
x + y mph
Distance = speed × time
Distance covered downstream is
32 = 2(x + y)
16 = x + y - - - - - - - - - - - -1
The return trip against the current takes sixteen hours.
Its total speed would be x - y mph
Distance = speed × time
Distance covered on return trip is
32 = 16(x - y)
2 = x - y - - - - - - - - - - - -2
Adding equation 1 and equation 2, it becomes
18 = 2x
x = 18/2 = 9 mph
Substituting x = 9 into equation 1, it becomes
16 = 9 + y
y = 16 - 9 = 7 mph
Answer:
D) 2/3
Step-by-step explanation:
Constant of proportionality formula:
k = y/x
8/12 = 2/3
10/15 = 2/3
12/18 = 2/3
14/21 = 2/3
