Because we're creating a 95% confidence interval, this means we have two tails of 2.5%. When we look up 0.025 in the Z table (click to open) , we find that it corresponds to a z-score of 1.96. After plugging everything into the equation, we find a lower bound of 480.8 and an upper bound of 559.2.
As already noted, the speed of light (expressed in meters per second) means that light travels a distance of 9,460,528,000,000 km (or 5,878,499,817,000 miles) in a single year. This distance is known as a âlight yearâ, and is used to measure objects in the Universe that are at a considerable distances from us.
Light years. We need a different unit of measurement, because at these distances, kilometres are too small to be much use. One unit for measuring very big distances is the light year. This is the distance that light travels in a year, so 1 light year is about 9 500 000 000 000 km.Using this unit, we say that the star Proxima Centauri is about 4.2 light years away. Even using this unit, numbers in space get pretty big. You know what a kilometre is â you can walk that distance easily. 2  You know what 100 km is â thatâs how far a car could travel in an hour at the speed limit on a main road. 3  Travel more than 100 km above the surface of the Earth, and youâre in space, at the edge of the atmosphere.