You randomly select one card from a 52-card deck. Find the probability of selecting a black seven or a black jack. The probability is (Type an integer or a fraction. Simplify your answer.)

Step 1 ：There are 2 black sevens and 2 black jacks in a 52-card deck. So, the total favorable outcomes are 4.

Step 2 ：The total possible outcomes are 52 (since there are 52 cards in a deck).

Step 3 ：The probability of an event is calculated as the ratio of the number of favorable outcomes to the number of possible outcomes.

Step 4 ：So, we need to calculate the ratio \(\frac{4}{52}\).

Step 5 ：Simplify the fraction \(\frac{4}{52}\) to \(\frac{1}{13}\).

Step 6 ：Final Answer: The probability of selecting a black seven or a black jack from a 52-card deck is \(\boxed{\frac{1}{13}}\).