$($b$)$ Compare the average cost of tablets with a Windows operating system to the average cost of tablets with an Android operating system.

The average cost of a tablet with a Windows operating system is $ $.$ The average cost of a tablet with an Android operating system is $ Windows operating systems cost than tablets with an Android operating system, on average.

$($c$)$ What percentage of tablets use a CPU manufactured by Nvidia?

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$($d$)$ What percentage of tablets use an Android operating system?