The monthly fuel bills (in $) of a random sample of 50 motorists in a certain city in the US, who commute to work daily by car, was recorded in a recent survey. The data is presented in the table below.

Class Frequency

250 -310 12

310 -370 10

370-430 9

430-490 4

490-550 7

550-610 2

610-670 6

For the grouped data, calculate each of the following:

(1.1) Mean (2 Marks)

(1.2) Mode (3 Marks)

(1.3) Median (4 Marks)

(1.4) Variance (4 Marks)

(1.5) Standard Deviation (2 Marks)

Show all your workings and see attached formulas.