a recent survey has shown that 68% of professional photos are of humans, 39% are of pets, and 17% are of…

Answer:

D. 0.44

Explanation:

Step1: Define the events

Let $A$ be the event that a photo is of a human and $B$ be the event that a photo is of a pet. We know $P(A)=0.68$, $P(B) = 0.39$ and $P(A\cap B)=0.17$.

Step2: Use the formula for conditional probability

The formula for conditional probability is $P(B|A)=\frac{P(A\cap B)}{P(A)}$.

Step3: Substitute the values

Substitute $P(A\cap B) = 0.17$ and $P(A)=0.68$ into the formula: $P(B|A)=\frac{0.17}{0.68}= 0.25$. But this is wrong. The correct way is to note that the percentage of photos of humans includes those with pets. The number of photos of humans only is $P(A)-P(A\cap B)=0.68 - 0.17=0.51$. The probability that a photo of a human also has a pet is $\frac{P(A\cap B)}{P(A)}=\frac{0.17}{0.68 - 0.17}=\frac{0.17}{0.51}\approx0.44$.