How do you calculate the probability of drawing a black card from a deck?

The probability of drawing a black card from a standard deck is 1/2 or 50%.

A standard deck of cards consists of 52 cards, which are divided into four suits: hearts, diamonds, clubs, and spades. Hearts and diamonds are red suits, while clubs and spades are black suits. Each suit contains 13 cards, so there are 13 clubs and 13 spades, making a total of 26 black cards in the deck.

To calculate the probability of drawing a black card, you need to divide the number of favourable outcomes (black cards) by the total number of possible outcomes (all cards in the deck). In this case, the number of favourable outcomes is 26 (the black cards), and the total number of possible outcomes is 52 (the total number of cards).

The formula for probability is:
\[ \text{Probability} = \frac{\text{Number of favourable outcomes}}{\text{Total number of possible outcomes}} \]

Substituting the numbers, we get:
\[ \text{Probability} = \frac{26}{52} \]

This fraction can be simplified by dividing both the numerator and the denominator by their greatest common divisor, which is 26:
\[ \frac{26}{52} = \frac{26 \div 26}{52 \div 26} = \frac{1}{2} \]

So, the probability of drawing a black card from a standard deck is 1/2. This can also be expressed as 0.5 or 50%, meaning there is an equal chance of drawing a black card or a red card from the deck.