Question

Thomas wants to invite Madeline to a party. He has 80% chance of bumping into her at school. Otherwise, he'll call her on the phone. If he talks to her at school, he's 90% likely to ask her to the party. What is the probability of Thomas inviting Madeline to the party over the phone?

Answer 1

Recall that the probability must add 1, therefore:

`0.6+x=1`

Solving for x, we get:

`\begin{gathered} x=1-0.6 \\ x=0.4 \end{gathered}`

Therefore, the probability of Thomas inviting Madeline to the party over the phone is:

`0.2\cdot0.4=0.08`

or 8%.