def interquartile_range_checker(train_user: list) -> float:
    train_user.sort()
    q1 = np.percentile(train_user, 25)
    q3 = np.percentile(train_user, 75)
    iqr = q3 - q1
    low_lim = q1 - (iqr * 0.1)
    return low_lim