If the average daily temperature in Juneau, Alaska, during the first days of January was , what must the daily average be during the remainder of the month if Juneau’s January average is to match the historical average of ?
Source: NCTM Mathematics Teacher 2008
Let represent the respective daily temperatures of day of January in Juneau, Alaska.
By definition of average we want
Substitute the value of the average daily temperature during the first twenty days
Multiply by and divide by
The average daily temperature for the remaining days of January should be if the Juneau’s January average is to match the historical average of .