= Solution
With the supplied angles, $c_{13}^4\sin^22\theta_{12}=0.70545$ and $\sin^22\theta_{13}=0.11698$. At $E=3\,\mathrm{MeV}$ and with the two atmospheric-scale splittings approximated by a common $3\times10^{-3}\,\mathrm{eV}^2$, the requested sketch is represented by
$$
\boxed{P_{ee}(L)\simeq1-0.70545\sin^2(0.0337849L)-0.11698\sin^2(1.26693L),\qquad L\text{ in km}.}
$$
The fast period is $2.480\,\mathrm{km}$ and its first <Neutrino oscillation>[disappearance] maximum is at $1.240\,\mathrm{km}$. The slow period is $92.99\,\mathrm{km}$, giving slow minima near $46.49$ and $139.48\,\mathrm{km}$. At each baseline the fast <Neutrino oscillations>[oscillations] lie between $1-0.70545\sin^2(0.0337849L)$ and that value minus $0.11698$. Averaging over unresolved fast <Neutrino oscillations>[oscillations] subtracts half that <Probability amplitude>[amplitude], rather than erasing the slow <Neutrino oscillation>[oscillation].
The equal atmospheric splittings are an approximation: exact squared <masses> require $\Delta m_{13}^2=\Delta m_{12}^2+\Delta m_{23}^2$. For example, choosing magnitudes $\Delta m_{31}^2=3.00\times10^{-3}$ and $\Delta m_{21}^2=0.08\times10^{-3}\,\mathrm{eV}^2$ gives $\Delta m_{32}^2=2.92\times10^{-3}\,\mathrm{eV}^2$. This changes the fine fast pattern while retaining the two physical scales. The figure deliberately displays the source's common-frequency approximation and labels the fast-averaged curve separately from the monoenergetic result.
\Image[/past-exam-of-the-particle-physics-course-of-the-university-of-oxford/2017-reactor-oscillation-scales.png]
{title=Vacuum electron-antineutrino survival at the supplied reactor energy and mixing parameters}
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