Explanation:
if you gave us the whole information, then we have 4 cards with the values : 4, 5, 6 and 7.
the probabilty to pick the card with the value 4 is the same as the probabilty to pick a card with value less than 5.
in both cases there is only one card for the desired outcome : 4.
therefore, P(4 or less than 5) = P(4)
a probability is always the ratio
desired cases / totally possible cases
so, in our case the probabilty to pick one specific card out of a total of 4 cards is
1/4
and so, the probability to pick 4 is
P(4) = 1/4.