Question

A wildlife photographer photographs a crocodile and then paddles against a river current for 6 km. Then, hoping to photograph a hippopotamus, she paddles 15 km across a lake. She paddles across the lake for one hour longer than she paddled up the river. Find the speed of the boat as she paddles the lake if the river current is 2 km/h.

Answer 1

Answer:

5 or 6

Step-by-step explanation:

So I did it in a different way than shown in rsm classes. I said that the speed was x-2 and x.

then I said the distance was 6 and 15. If the time taken was 1 hour more, then we can come up with this equation:

Since the time is 6/x-2 or 15/x

15/x-6/x-2=1

multiply everything to get a common denominator then cancel it out to get

(15x-30)-6x=x^2-2x

11x-30=x^2

x^2-11x+30=0

(x-5)(x-6) is factored form.

so x=5 or x=6. this means that the speed of the boat is either 5km/h or 6 km/h