TITLE: How to calculate an overall 5 star rating based on other weighted 5 star ratings
QUESTION [6 upvotes]: I have these 3 ratings.  I want to combine them to produce an overall rating out of 5.  The overall rating can be a float, so no rounding is necessary, but it cannot be negative.  I'm just not sure how to do it.
Technical Rating from 1 to 5, weighting 2:1  (i.e A rating of 5 equals 10)
Production Rating from 1 to 5, weighting 1:1
Content Rating from 1 to 5, weighting 3:1
Any hints or advice would be awesome, thanks.

REPLY [7 votes]: You could try something like $$\frac{2TR + PR + 3CR}{6}.$$
Try it with various examples including 

$(5,5,5)$ to give a result of $5$, 
$(1,1,1)$ to give a result of $1$,
$(4,1,1)$ to give a result of $2$,
$(1,4,1)$ to give a result of $1.5$,
$(1,1,4)$ to give a result of $2.5$,

to see the effect.