A huge circular arc of length 4.4 ly subtends an angle 4 s at the centre of the circle. How long it would take for a body to complete 4 revolution if its speed is 8 AU per second?\\
Given: $1\mathrm{ly} = 9.46 \times 10^{15}\mathrm{~m}$\\
$1\mathrm{AU} = 1.5 \times 10^{11}\mathrm{~m}$\\
(1) $3.5 \times 10^{6}\mathrm{~s}$\\
(2) $4.5 \times 10^{10}\mathrm{~s}$\\
(3) $4.1 \times 10^{8}\mathrm{~s}$\\
(4) $7.2 \times 10^{8}$