Probability of any one of the 10 persons being invited for the first interview = \(\frac{1}{10}\)
Probability(Neither Paul nor Jen are at the first interview) = 1 – Probability(Either Paul or Jen are at the first interview)
Probability of either Paul or Jen being invited first = \(\frac{1}{10} + \frac{1}{10}\) = \(\frac{2}{10}\).
Note that if Paul is invited, Jen is not and vice versa and that is why we just have to add \(\frac{1}{10}\) with \(\frac{1}{10}\).
Therefore, probability that neither Paul nor Jen are at the first interview = 1 – \(\frac{2}{10}\) = \(\frac{8 }{ 10}\) = \(\frac{4}{5}\).
The correct answer option is D.
Hope that helps!
Aravind BT