(i)[2]
Find the mean age for the full set of $24$ cars.
(ii)[4]
Find the standard deviation of the ages of the complete set of $24$ cars.
Mathematics 9709 · AS & A Level · Sampling and estimation
Sampling and estimation — practice question
Red Street Garage is offering 9 used cars for sale. Fairwheel Garage is offering 15 used cars for sale. The mean age of the cars at Red Street Garage is $3.6$ years and the standard deviation is $1.925$ years. For Fairwheel Garage, $\Sigma x = 64$ and $\Sigma x^2 = 352$, where $x$ represents the age of a car in years.
Worked solution & mark scheme
This 6-mark question has a full step-by-step worked solution and mark scheme. One marking point: “Multiply $3.6 \times 9$, then add $64$, and afterwards divide by $24$” …
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