Question

Five of the 100 digital video recorders (DVRs) in an inventory are known to be defective. What is the probability you randomly an item that is not defective?

Answer 1

Total number of DVRs= 100

No. of DVRs defective =5

No. of DVRs not defective= 100-5 = 95

P(of device not defective= 95/100

19/20

Answer 2

Given :

Number of digital video recorders = 100

Number of defective video recorders = 5

To find : Probability that an item that is not defective = ?

Solution :

Number of video recorders that are not defective = $100-5=95$

So, Probability of getting an item is not defective is given by

$\dfrac{\text{Number of good item}}{\text{Number of video recorders}}=\dfrac{95}{100}=0.95$

Hence, the required probability is 0.95.