What Are the Frequencies of the First Two Overtones in a Closed Air Column?

[Exhonour]

Homework Statement

An air column closed at one end has a fundamental frequency of 500Hz. What are the frequencies of the first two overtones?

Answers:
1500Hz
2500Hz

Homework Equations

Overtone:
f = (n+1)f
n = overtone

Harmonic:
f = nf

The Attempt at a Solution

f1 = (n+1)f
= (1+1)500
= 1000Hz

f2 = (2+1)500
= 1500Hz
Im not getting it, what am I doing wrong? Its asking for frequency of overtone #1/overtone #2, I put the right values in the equation but I still don't get the right answer.

 

[hage567]

In a pipe closed at one end, only odd harmonics occur, so if the fundamental frequency is f₁, then the frequencies of the harmonics will be f_n = nf₁, where n = 3,5...