Solution
The picture below shows the whole 52 standard deck
Let B denotes the events of cards that is less than 7
We will include the aces in the set B, because we are told to assume that they are low cards
B = {all 2, all 3, all 4, all 5, all 6, all aces}
n(B) = 24
Let A denotes the events of cards that is a 5 of diamonds
A = {5diamond}
n(A) = 1
A n B = {5diamonds}
n(A n B) = 1
The probability
Note: Conditional Probability Formula
From the question, we want to find the probability of A given B
Therefore, the answer is