Paper 6 October/November 2010 MATHEMATICS (9709/61) A Levels
لطفا برای اطمینان از عملکرد و تجربه بهتر از مرورگرهای مدرن و به روز مانند کروم یا فایرفاکس استفاده کنید.

When Ted is looking for his pen, the probability that it is in his pencil case is 0.7. If his pen is in his pencil case he always finds it. If his pen is somewhere else, the probability that he finds it is 0.2.
Given that Ted finds his pen when he is looking for it, find the probability that it was in his pencil case.