help with functions/stats/trig question?

Question

the mean average monthly rainfall in orlando, florida for the first 5 months of 2005 is 2.94", while the mean average rainfall for the last 7 months was 5.66". Compute the weighted average monthly rainfall in orlando for 2005. round to hundredths

Answer 1

A quick note, "mean" and "average" mean the same thing, so we don't have to say both. So we have data for all 12 months, even if it is a bit wonky. What we're going to do is multiply both of the averages by the portions of the year that they cover, and then add them. The first measurement is for 5 of the 12 months, so we multiply by 5/12. The second is for 7 of the 12 months, so we'll multiply by 7/12. We get: (2.94 * 5/12) + (5.66 * 7/12), which comes out to 4.53" monthly rainfall for all of 2005.