def solution(ratio: float = 0.1) -> int:

    j = 3
    primes = 3

    while primes / (2 * j - 1) >= ratio:
        for i in range(j * j + j + 1, (j + 2) * (j + 2), j + 1):
            primes += is_prime(i)
        j += 2
    return j