#include <bits/stdc++.h>
#include <math.h>

using namespace std;

// The number of tickets purchased by each student for the University
// X vs. University Y football game follows a distribution that has a
// mean of mu = 2.4 and a standard deviation of sigma = 2.0.


// A few hours before the game starts, 100 eager students line up to
// purchase last-minute tickets. If there are only 250 tickets left,
// what is the probability that all students will be able to purchase
// tickets?


// mu' (mean) = n * mu
// sigma' (stddev) = sqrt(n) * sigma

int main()
{
    int n = 100 /* students */;
    int mean = n * 2.4 /* tickets */;         // mu
    int stddev = sqrt(n) * 2.0 /* tickets */;  // sigma

    // Probability P(X <= x)
    auto normalCDF = [](double x, double mean, double stddev)
    {
        double val = (x - mean)/(stddev * sqrt(2));
        return 0.5 * (1 + (erf(val)));
    };
    
    double answer_1 = normalCDF(250 /* tickets */, mean, stddev);

    cout << fixed << setprecision(4) << answer_1 << endl;
}