Answer:[tex]\dfrac{4}{7}[/tex]
Step-by-step explanation:
Formula for conditional probability:
[tex]P(B|A)=\dfrac{P(B\cap A)}{P(A)}[/tex]
Given: n (donuts) = 140
n(donuts and cinnamon rolls) = 80
Now, the probability that they order cinnamon rolls given that we = know a person orders donuts will be :
[tex]P(cinnamon\ rolls |\ donuts)=\dfrac{n(cinnamon\ and \ donuts)}{n(donuts)}\\\\=\dfrac{80}{140}\\\\=\dfrac{4}{7}[/tex]
Required probability= [tex]\dfrac{4}{7}[/tex]