Prorated Percentage Calculation

I need help with calculating a prorated percentage:

at 80% of plan pay 5% of salary
at 100% of plan pay 10% of salary
at 120% of plan pay 15% of salary

I have to prorate % of salary to pay based on the % of plan achieved.
(ie: 90% of plan = 7.50% of salary)

Is there a formula I can use to do this easily?

Thanks again!

"macmichele" <[email protected]> wrote in message
news:[email protected]...
>I need help with calculating a prorated percentage:
>
> at 80% of plan pay 5% of salary
> at 100% of plan pay 10% of salary
> at 120% of plan pay 15% of salary
>
> I have to prorate % of salary to pay based on the % of plan achieved.
> (ie: 90% of plan = 7.50% of salary)
>
> Is there a formula I can use to do this easily?
>
> Thanks again!
>

=0.05 + (X-0.8)/4

where X is the % of plan achieved as a decimal (90%=0.9, etc.).'

one way


=IF(C1<60,0,(C1-60)*0.25)

where c1 is the cell to enter the variable
if c1 is smaller than 60 it will not deduct anything.

--
Greetings from New Zealand
Bill K

"macmichele" <[email protected]> wrote in message
news:[email protected]...
>I need help with calculating a prorated percentage:
>
> at 80% of plan pay 5% of salary
> at 100% of plan pay 10% of salary
> at 120% of plan pay 15% of salary
>
> I have to prorate % of salary to pay based on the % of plan achieved.
> (ie: 90% of plan = 7.50% of salary)
>
> Is there a formula I can use to do this easily?
>
> Thanks again!
>