A contractor needs to complete a given work in 24 days. For every day that he finishes ahead of time, he gets an incentive 'I' and for every day that he finishes behind time, he needs to pay a penalty 'P'. He has a choice of two workers who work as follows: A completes the work in 24 days for 75% of the time and in 30 days for 25% of the time. B comlpetes the work in 20 days for 60% of the time and in 30 days for 40% of the time. At what ratio of P to I will the conctractor be indifferent of using A or B?