2. A kayaker travels 4 miles upstream and 4 miles downstream in a total of 6 hours. In still
water, the kayaker can travel at an average speed of 2.3 mi/h.
Determine the average speed of the river's current.

The average speed of the river's current is 1.49107 miles per hour

Solution:

Given that,

Upstream distance = 4 miles

Downstream distance = 4 miles

If the speed of a boat in still water is u km\hr and the speed of the stream is v km/hr then:

Speed downstream = u + v km\hr

Speed upstream = u - v km\hr

From given,

Speed in still water = 2.3 miles per hour

u = 2.3

Therefore,

speed downstream = 2.3 + v

Speed upstream = 2.3 - v

The total time is 6 hours

Therefore,

Thus we get,

Thus the average speed of the river's current is 1.49107 miles per hour

the balance is found at the link

step-by-step explanation:

1. d.90

2. e. none of these (80)

3. a. 0

4. b. 6

5. e. none of these (10)

6. a. 5