Paper 7 May/June 2011 MATHEMATICS (9709/73) A Levels
لطفا برای اطمینان از عملکرد و تجربه بهتر از مرورگرهای مدرن و به روز مانند کروم یا فایرفاکس استفاده کنید.

People arrive randomly and independently at a supermarket checkout at an average rate of 2 people every 3 minutes.
a) Find the probability that exactly 4 people arrive in a 5-minute period.
At another checkout in the same supermarket, people arrive randomly and independently at an average rate of 1 person each minute.
b) Find the probability that a total of fewer than 3 people arrive at the two checkouts in a 3-minute period.