Two circular linear polarisers are placed coaxially. The transmission axis of the first polariser is $30°$ from the vertical while the second one is at $60°$, both in the clockwise sense. If an unpolarised beam of light of intensity, $I=20 \mathrm{W} {\mathrm{m}}^{-2}$ is incident on this pair of polarisers, then the intensities $I_1$ and $I_2$ transmitted by the first and the second polarisers, respectively, will be close to,