The speed of surface waves in water decreases as the water becomes shallower. Suppose

The speed of surface waves in water decreases as the water becomes shallower. Suppose waves travel across the surface of a lake with a speed of 2.1 m/s and a wavelength of 1.9 m. When these waves move into a shallower part of the lake, their speed decreases to 1.9 m/s, though their frequency remains the same. Find the wavelength of the waves in the shallower water.