Answer:
Pr(tablet given smartphone) = 18%
Step-by-step explanation:
Let:
probability that the student has a smartphone = Pr(smart phone)
Pr(smart phone) =0.71
the probability that the student has a tablet = Pr(tablet)
Pr(tablet) = 0.28
the probability the student has both = Pr(both)
Pr(both) = 0.13
the probability a student has a tablet given they have a smartphone = Pr(tablet given smartphone)
Pr(tablet given smartphone) = Pr(tablet & smartphone)/Pr(smart phone)
Pr(tablet given smartphone) = 0.13/0.71
Pr(tablet given smartphone) = 0.183 = 18.3%
Pr(tablet given smartphone) = 18%