How Do You Calculate Wavelength in Doppler Effect Scenarios?

[lha08]

Homework Statement

source emits sound with a characteristic frequency of 640 Hz. Calculate the observed frequency and the wavelength between source and observer in each of the following situations.
a) The observer approaches a stationary source at 57 m/s
b) Both the source and observer move towards each other at 28.5 m/s

Homework Equations

The Attempt at a Solution

I already managed to calculate for the frequency: 747.29 Hz but can anyone explain to me how to find the wavelength because what i thought was that i could simply do 340/747.29 which is wrong..Help please!

 

[Shukie]

What are the situations? With the information given we can't do anything.

 

[lha08]

What are the situations? With the information given we can't do anything.

my bad, no wonder no one was replying :P

 

[Doc Al]

Since the source is stationary, the wavelength doesn't change.