Wavelength Calculation in a Ripple Tank with Varying Speeds

[rrosa522]

Homework Statement

In a ripple tank, you measure the speed of a wave to be 12 cm /s in the deep section and 9.0m/s in the shallow section. If the waves in the deep section that are 11.5 cm long cross over to the shallow section, what would be the wavelength in the shallow section

Homework Equations

The Attempt at a Solution

I am not even sure how to start this question, how do i find the wavelength without frequency, and what exactly does this even question mean?

 

[Miles Whitmore]

The frequency will be the same in the deep end as the shallow end. You have enough information to be able to find it in one end of the tank.