Calculate how long Joshua needs to work in order to afford the HDB apartment as he need to set aside $25,000 in his ordinary account to buy a 4-room HDB apartment and examine how he can possibly accelerate this process given the information below. State the assumptions you have made.

- his starting salary is $3,500 per month

- CPF contribution rate (both employer and employee) for his age group is 37% Ordinary account = 60% Medisave account = 22% Special account = 18%

- interest rate paid by CPF Board on members ordinary account is 2.5% per annum, compounded monthly.