Any individual employed in state service on a part-time basis whose employment calls for 30 hours or more work in a normal calendar week, and whose position is anticipated to have a duration of 6 months or more, shall be entitled to elect to receive such health and dental benefits as are afforded full-time state employees, except that the state's share of the cost of such benefits shall be decreased by a factor equal to the difference between 37.5 hours and the number of hours such individual works in a normal calendar week, divided by 37.5 hours. The remaining costs of health and dental benefits which any such individual elects to receive pursuant to this section shall be withheld from such individual's salary as a payroll deduction.