How to Calculate the working days and return the value in terms of day and hours like "4.75"

[DagimAsnake]

I have made a formula to calculate the date difference between start date and end date and returns a value in terms of day and hours as a fraction like "4.75" here is the formula

IF(

  {End Date} >= {Start Date},

  ROUND(DATETIME_DIFF({End Date}, {Start Date}, 'hours') / 24, 2),

  'Invalid'

)
But right know i want to change the above formula only for working days tho, i know there is a formula to calculate the working days difference  WORKDAY_DIFF({Start Date}, {End Date}) hence it returns in terms of days only like "4" but i want to return the hour also like "4.71"

[joshsorenson]

The hard part of this is you would need to determine the hours in a day that are working hours too which the formulas aren't really meant to account for.