import math


def interval95(acc:float, n_data:int) -> float:

    """
    Calculates the confidence interval 95% on a given number of samples.

    Args:
        acc (float): The accuracy.
        n_data (int): The number of samples.

    Returns:
        float: The confidence interval.
    """    
    
    bound = 1.96 * math.sqrt((acc*(1-acc)) / n_data)

    return bound