use proconio::{fastout, input};

#[fastout]
fn main() {
    input! { t: usize }

    for _ in 0..t {
        let ans = solve();
        println!("{ans:.15}");
    }
}

fn solve() -> f64 {
    input! {
        n: usize, m: usize, k: usize
    }

    let mut p = 0.0;

    let a = k.div_ceil(m);

    // 最後まではずれを引かない
    let q = (n - a) as f64 / n as f64;
    let rest = k.saturating_sub((n - 1) * m);
    let r = (m - rest) as f64 / m as f64;
    p += q * r;

    if m > 1 {
        // 途中ではずれ
        let q = (1.0 - q) / m as f64;
        let rest = k.saturating_sub((n - 1) * m + 1);
        let r = (m - 1 - rest) as f64;
        p += q * r;
    }

    p
}

// Nの総和に対する制約がなかった。。。