the answer says there will be 4 hours ( from 9am till 1pm) until 40% of the pies are sold. however we have F(t) - 0.3729 or 37.29% ( correspondingly, S(t) =0.6271 or 62.71%), which is short of 40%. so it should be more than 4 hours then? what do you think?
When we are looking at S(t)=0.6271, it does mean that we have not yet sold more than 40% of the buns.But this interval corresponds to [2,4) and by the time we reach 4 hours, we are selling 40% of the buns as S(t)=0.4493 i.e just short of 60%. If you want to calculate using F(t), it means that 40% of the buns were not yet sold till we reach 4 hrs duration.But as soon as 4 hrs get over we are selling 40% of the buns.It cant be more than 4 hrs as the transition takes place at duration 4 and it remains the same throughout the interval... Hope this helps...
