Answer:
The question has some probable errors, but I will illustrate how to solve a problem such as this.
Step-by-step explanation:
The speed of a wave is given by Speed = (Distance)/(Time), or, alternatively, Speed = Wavelength x Wave Frequency
In this problem, we are given a speed of "3 x 10 m/s." I suspect that the speed should have read 3x10^8 m/s, the speed of light. This says the speed is 30 m/s.
The frequency reads "998 x 10% H2." I can't guess what this was supposed to be, but 998 x 10% H2 means "99.8 H2." That doesn't seem to have anything to do with wavelength. Find the correct frequency, plug it into the equation with the correct speed, such as:
3x10^8 m/s = (9.98x10^2 cycles/sec)(Wavelength)
Wavelength = (3x10^8 m/s)/((9.98x10^2 cycles/sec) = 3.01x10^5 meters
Use the correct numbers, and you should be able to calculate the correct wavelength.