Question 170096
A new virus is released on the internet; the administrator of a department's Local Area Network ( LAN) is given five minutes by a manager to estimate the impact. The administrator samples 15 of the PCs connected to the LAN, and finds that 9 are infected; use proportion to estimate the number of infected PCs if there are a total of 202 PCs connected to the LAN. 
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Use a proportion:
[9 infected/15 sampled] = [x infected/all the PCs]

(9/15) = (x/202)
x = 202(9/15)

x = 202(3/5)
x = 121.2
Round down to get x = 121 infected PC's out of 202
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Cheers,
Stan H.