Answer
$P$(device is capable of monitoring power quality and is wired up for that purpose) =$9$%
Work Step by Step
Event A:Device can monitor the quality of the power running through the device.
Event B:Equipment is wired up. (given 90% do not wire the equipment i.e 10% wire the equipment)
$P$(device is capable of monitoring power quality and is wired up for that purpose) = $P$(A and B) = $P$( A ∩ B )
$P$( A ∩ B ) = $P$(A)$\times$$P$(B).
$P$( A ∩ B ) =$ 0.9\times0.1$
$P$( A ∩ B ) = 0.09 = $9$%.
