Show that $\lambda=\exp (\mu / k T)=n V_Q$ for an ideal gas, valid where $\lambda \ll 1$; here $\mu$ is the chemical potential, $n$ is the gas density and
$$
V_Q=\left(h^2 / 2 \pi m k T\right)^{3 / 2}
$$
is the quantum volume. Even if you cannot prove this, this result will be useful in other problems.