Question

The Hudson River flows at a rate of 3mph. A patrol boat travels 60 mi upriver and returns (another 60mi ) What is the speed of the boat in still water? can somebody there help me to do this?

Answer 1

wait, how long does the boat take total trip?

Answer 2

yes

Answer 3

you are missing info. We need the total time of the trip

Answer 4

The Hudson River flows at a rate of 3mph. A patrol boat travels 60 mi upriver and returns (another 60mi ) in a total time of 9hr.What is the speed of the boat in still water? can somebody there help me to do this?

Answer 5

Alright, now we have the time.
Let S = speed of patrol boat in still water
and T = time traveled going up river
.
(S-3)T = 60
(S+3)(9-T) = 60
.
(S+3)(9-T) = 60
9S+27-ST-3T = 60
.
(S-3)T = 60
T = 60/(S-3)
.
9S+27-ST-3T = 60
9S+27-S(60/(S-3))-3(60/(S-3)) = 60
9S(S-3)+27(S-3)-S(60)-3(60) = 60(S-3)
9S^2-27S+27S-81-60S-180 = 60S-180
9S^2-27S+27S-81-60S = 60S
9S^2-81-60S = 60S
9S^2-81-120S = 0
9S^2 - 120S - 81 = 0
3S^2 - 40S - 27 = 0
.
you must either factor or apply the quadratic formula. In this case, you can only apply the quadratic formula. It will give you two answers -- one negative and one positive. Since, a negative speed won't make sense here, the only one that makes sense is the positive answer.
S = 13.98 mph
.

Answer 6

thank you