Paper 6 May/June 2011 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.

In Scotland, in November, on average 80% of days are cloudy. Assume that the weather on any one day is independent of the weather on other days.
a) Use a normal approximation to find the probability of there being fewer than 25 cloudy days in Scotland in November (30 days).
b) Give a reason why the use of a normal approximation is justified.