Consider a renewal process with the lifetimes $X_1,X_2,\ldots$ having the continuous uniform distribution $\mathrm{Unif(1.5,4)}$. Determine the asymptotic expression for the expected number of renewals up to time $t$:
My attempt:
Using the formula $M(t) = \frac{t}{\mu} + \frac{\sigma^2-\mu^2}{2\mu^2}+o(1)$.
Calculating for $\mu$ and $\sigma^2$ since it follows $\mathrm{Unif(1.5,4)}$, $\mu = 2.75$ and $\sigma^2 = \frac{6.25}{12}$ and so the equation yields $M(t) = \frac{t}{2.75} + \frac{\frac{6.25}{12}-2.75^2}{2\cdot2.75^2}+o(1)$
But this was marked as incorrect, most notably $\mu$. I do not know how what else I can do for this, I would appreciate any help in solving this.