Doppler Effect II (Both observer and source in motion)

[exi]

1. The problem statement, all variables and given/known data

You're flying in an aircraft at 46 m/s. An eagle flies directly towards you at 11 m/s. Speeds are relative to ground.

The eagle emits a cry at 3400 Hz, and the speed of sound is 330 m/s. What frequency do you hear?

2. Relevant equations

f_o = f_s\left( \frac{1\pm\frac{v_o}{v}}{1\mp\frac{v_s}{v}} \right)

Because the observer and source are both moving towards each other (presumably?),

f_o = f_s\left( \frac{1+\frac{v_o}{v}}{1-\frac{v_s}{v}} \right)

3. The attempt at a solution

Seems simple enough, but

f_o = 3400\left( \frac{1+\frac{46}{330}}{1-\frac{11}{330}} \right)

Works out to 4902.8213 Hz, a wrong answer. This problem seemed straightforward, but I'm not sure what I'm missing.

[Dick]

Check your math. That's not what I get.

[exi]

Check your math. That's not what I get.

Don't I feel silly, part 2.

4007.5235 Hz. I've got only one remaining shot at that problem; I didn't make any other conceptual mistakes, correct?

[Dick]

That's what I get, but I'm not claiming infallibility.

[exi]

That's what I get, but I'm not claiming infallibility.

It's correct.

Thanks much, sir; I'll just whistle and blame my calculator now.