Paper 6 May/June 2004 MATHEMATICH (9709/6) A Levels
لطفا برای اطمینان از عملکرد و تجربه بهتر از مرورگرهای مدرن و به روز مانند کروم یا فایرفاکس استفاده کنید.

Delip measured the speeds, $x{\text{ }}km$ per hour, of 70 cars on a road where the speed limit is $60{\text{ }}km$ per hour.
His results are summarised by $\sum {\left( {x - 60} \right)} = 245$.
a) Calculate the mean speed of these 70 cars.
His friend Sachim used values of $\left( {x - 50} \right)$ to calculate the mean.
b) Find $\sum {\left( {x - 50} \right)} $.
c) The standard deviation of the speeds…