The distance to a particular star, as measured in the earth's frame of reference, is 7.11 light years (1 light year is the distance light travels in 1 year). A spaceship leaves earth headed for the star, and takes 3.35 years to arrive, as measured by passengers on the ship.
(a) How long does the trip take, according to observers on earth?
(b) What distance for the trip do passengers on the spacecraft measure (Hint: What is the speed of light in units of ly/y)