Question

A coin is flipped 30 times. Find the variance (σ²) of the number of heads. Round to 1 decimal place.

A) 7.5
B) 15.0
C) 22.5
D) 30.0

Answer 1

To find the variance (σ²) of the number of heads when a coin is flipped 30 times, use the formula for variance: Variance (σ²) = n * p * (1 - p). Substitute the values and calculate to get the answer.

Step-by-step explanation:

To find the variance (σ²) of the number of heads when a coin is flipped 30 times, we need to use the formula for variance:

Variance (σ²) = n * p * (1 - p)

where n is the number of trials (30) and p is the probability of getting a head (0.5 for a fair coin).

Substituting the values into the formula, we get:

Variance (σ²) = 30 * 0.5 * (1 - 0.5) = 30 * 0.5 * 0.5 = 7.5

Therefore, the variance (σ²) of the number of heads when a coin is flipped 30 times is 7.5. The answer is option A.