In a lecture hall at a collage, the number of seats per row increased at a constand rate. the professor counts 21 seats in row 3 and 33 seats in row 7. how many sets are there in row 18?

  66 seats

Step-by-step explanation:

The rate of increase is ...

  (change in seats)/(change in rows) = (33 -21)/(7 -3) = 12/4 = 3 . . . seats/row

Then row 18 will have (18-3)·3 = 45 more seats than row 3, hence ...

  21 + 45 = 66 . . . . seats in row 18

An explicit formula for the number of seats can be written as ...

  s = 21 +3(n-3) = 12 +3n

For n=18, this is ...

 s = 12 + 3(18) = 12 +54 = 66 . . . seats in row 18

an advantage of the standard deviation is that it increases as the dispersion of the data increases. e. the interquartile range is preferred when the data are not skewed or no have outliers. an advantage of the standard deviation is that it uses all the observations in its computation.