# Knowing that the Earth's diameter is about "3 2/3" times the diameter of the moon, what is the angular diameter of the Earth as seen by an observer on the moon?

About ${1}^{\circ} 54 '$
You need a little more information, e.g. that the angular diameter subtended by the moon from Earth is about $31 '$ (i.e. just over ${0.5}^{\circ}$)
$31 \cdot \frac{11}{3} = \frac{341}{3} \approx 114 '$ or ${1}^{\circ} 54 '$