Paper 7 May/June 2010 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.

Each drink from a coffee machine contains $X{\text{ }}c{m^3}$ of coffee and $Y{\text{ }}c{m^3}$ of milk, where $X$ and $Y$ are independent variables with $X \sim N\left( {184,{\text{ }}{{15}^2}} \right)$ and $Y \sim N\left( {50,{\text{ }}{8^2}} \right)$. If the total volume of the drink is less than $200{\text{ }}c{m^3}$ the customer receives the drink without charge.
a) Find the percentage of drinks which customers receive without charge.
b) Find the…