Find the third quatile (Q3) if quartile deviation (QD) = 2.5
and first quartile (Q1.) = 18

qd = q3- q1/ 2

or, 2.5= q3- 18/ 2

or, 2.5× 2 = q3- 18

or, 5= q3- 18

or,q3= - 18 + 5

:. q3= 13

use an equation of ratios to determine the amount of gas needed to fill the tank.

    0.2             0.8

  =    

288.75             x

                                                              231 gal

so, 0.2x = (0.8)(288.75 gal), and x = = 1155 gal.

                                                                0.2

it would take 1155 gal. to fill the tank.

the cost would be

1155 gal         $3

* = $3465   (answer)

      1           1 gal

hope this you