International project appraisal

Dear Sir,

Penn co (thenical article question)
In the pppt calculation take the higher rate to determine 6 month,one year etc rates.

However when determining the free cash flow for the now the rate taken 150 the lower rate and then the higher rate for 6 month and year one etc.

I don’t get the logic starting with the lower rate and then the higher rate.

Could you please explain it?

Thank you,

Bizuayehu