In the same question using PPT the value of S1 from the formula is 1.53 but in printed answer in Kit taken 0.654 . Similar with S2 value 1.56 but in printed answer in Kit taken 0.6410.
If you want me to answer then you should ask in the Ask the ACCA Tutor Forum. This forum is for students to help each other.
The rates that you have calculated are $’s per GBP. If you are converting from GBP to $’s then (for time 1) you either multiply by 1.53 or you divide by 0.654 – it comes to the same. (1/0.654 = 1.53)