C++: 

#include <bits/stdc++.h>
#define ll long long
using namespace std;
double tbc(double arr[], ll n) {
    double sum = 0;
    for (ll i = 0; i < n; ++i) {
        sum += arr[i];
    }
    return sum / n;
}
double phantu(double arr[], ll n, double avg) {
    double nho = abs(arr[0] - avg);
    double nho2 = arr[0];
    for (ll i = 1; i < n; ++i) {
        double chia = abs(arr[i] - avg);
        if (chia < nho) {
            nho = chia;
            nho2 = arr[i];
        }
    }
    return nho2;
}

int main() {
    ll n;
    cin >> n;
    double arr[n];
    for (ll i = 0; i < n; ++i) {
        cin >> arr[i];
    }
    double avg = tbc(arr, n);
    cout <<  fixed << setprecision(2) << avg << endl;
    double chiacat = phantu(arr, n, avg);
    cout <<  fixed << setprecision(2) << chiacat << endl;
    return 0;
}

$#doanthevu$