A worker is paid $ 200 as basic wages plus $ 300 as D.A. per month. There is a contributory fund at 8 1/3% per cent and gratuity on the basis of half month's wages for each completed year of service. The firm has been paying one month's wages as bonus. The worker is entitled to 15 days leave with wages and he normally works 8 hours per day. Taking a month as equal to 25 working days, what is the wage per hour for costing purposes