A boat traveled downstream a distance of 152mi

Question

A boat traveled downstream a distance of 152 mi and then came back. If the speed was 7 mph and the total trip took 6 hours and 20 minutes, find the average speed of the boat relative to the water

Answer 1

Your question isn't clear on what exactly has a speed of 7 mph.

From the way this is written I will assume 7mph is the current speed.

 

distance = rate*time ...  d=rt

 

Downstream:  rate = boat speed + current speed = b+7

time = t

Upstream:  rate = boat speed - current speed = b-7

time = (6 1/3 - t)

 

1)  Downstream:  152 = (b+7)t

2)  Upstream:  152 = (b-7)(6 1/3 - t)

 

multiply through the parenthesis

 

equaton 1:  bt + 7t = 152

equation 2: 19b/3 -bt - 133/3 + 7t = 152