Coin Toss Probability Formulas | List of Coin Toss Probability Formulas You Should Know - BYJUS

# Coin Toss Probability Formula

Tossing a coin is quite a common activity to help us make a decision. The toss of a coin will always result in one of two possible outcomes. With the formula to calculate the probability linked to a coin toss, we will be able to find out the probability of any experiment that involves tossing a coin....Read MoreRead Less

### Formula to Calculate Probability of a Coin Toss

The probability of any event that is supposed to or may happen is defined as the measurement of chances, or in simpler terms, the likelihood of this event occurring.

Now, the formula to calculate the probability of a coin toss can be defined as,

$$Probability=\frac{Number~of~favorable~outcomes}{Total~number~of~outcomes}$$

There are two possible outcomes when a coin is tossed. So, by applying the probability formula,

The probability of getting heads after the toss is: P(Heads) = P(H) = $$\frac{1}{2}$$

The probability of getting tails after the coin toss is: P(Tails) = P(T) = $$\frac{1}{2}$$ ### Solved Examples

Example 1: If a coin is tossed thrice, what is the probability of getting at least two tails?

Solution:

When a coin is tossed thrice, the possible outcomes are {HHH, TTT, HHT, HTH, THH, HTT, TTH, THT}

Total number of outcomes is 8.

The number of desired outcomes of getting two tails is {HTT, TTH, THT, TTT}

The count for the number of favorable outcomes is 4.

Thus, the probability of getting at least two tails = $$\frac{Number~of~favorable~outcomes}{Total~number~of~outcomes}$$

= $$\frac{4}{8}$$

= $$\frac{1}{2}$$

The probability of getting at least two tails is $$\frac{1}{2}$$.

Example 2: What is the probability of getting at least one heads when two coins are tossed simultaneously?

Solution:

When two coins are tossed, the possible outcomes will be {HH, TT, HT, TH}.

Hence, the total number of possible outcomes = 4

The number of desirable outcomes for getting at least one heads will be {HT, TH} outcomes.

Thus, the number of favorable outcomes = 2

Hence, the probability of getting at least one heads = $$\frac{Number~of~favorable~outcomes}{Total~number~of~outcomes}$$

= $$\frac{2}{4}$$

= $$\frac{1}{2}$$

The probability of getting at least one heads is $$\frac{1}{2}$$.

Example 3: What is the probability of getting the same face when a coin is tossed twice?

Solution:

When two coins are tossed, the possible outcomes will be {HH, TT, HT, TH}.

Thus, the total number of outcomes = 4

The desirable outcomes of the same face will be {HH, TT}

Number of desirable outcomes = 2

Thus the probability of getting the same face = $$\frac{Number~of~favorable~outcomes}{Total~number~of~outcomes}$$

= $$\frac{2}{4}$$

= $$\frac{1}{2}$$

Thus, the probability of getting the same face is $$\frac{1}{2}$$.