A factory makes a large number of ropes with lengths either 3 m or 5 m. ?
A factory makes a large number of ropes with lengths either 3 m or 5 m. There are four times as many
ropes of length 3 m as there are ropes of length 5 m.
One rope is chosen at random. Find the expectation and variance of its length
The answer for expectation is 3.4 but how to find it?
- PuzzlingLv 72 months agoFavorite Answer
Imagine a representative sample of 4 ropes (3m) and 1 rope (5m).
Calculate the total length:
(4 * 3) + 5 = 17
Divide by 5 ropes in the representative sample:
17/5 = 3.4