There are total of 10 persons of which P1 is always selected and hence P4 and P5 are not be included in the arrangement. Now, person left =10−3=7 (as P1 is already selected and P4 and P5 are not selected) ∴ To select4 persons from 7 persons total ways =‌7C4 Also, these 5 persons can be arranged in 5! ways. ∴ Required ways of arrangement =‌7C4×5!