Paper 7 May/June 2008 MATHEMATICH (9709/7) A Levels
لطفا برای اطمینان از عملکرد و تجربه بهتر از مرورگرهای مدرن و به روز مانند کروم یا فایرفاکس استفاده کنید.

The marks of candidates in Mathematics and English in 2009 were represented by the independent random variables $X$ and $Y$ with distributions $N\left( {28,{\text{ }}{{5.6}^2}} \right)$ and $N\left( {52,{\text{ }}{{12.4}^2}} \right)$ respectively. Each candidate’s marks were combined to give a final mark $F$, where $F = X + \frac{1}{2}Y$.
a) Find $E\left( F \right)$ and $Var\left( F \right)$.
b) The final marks of a random sample of 10 candidates from…