l2p4-spd

%Sa se calculeze probabilitatea ca dintr-o 100 de aruncari a unei monezi
%numarul de aparitii a fetei cap sa fie cuprins intre : a)35-65 b)40-60
%c)45-55


clc
clear
help p3.m

n=100;
p=1/2;

q=1-p;
X=zeros(2,n+1);
F=zeros(1,n+1);

for k=0:n
    x(1,k+1)=k;
    x(2,k+1)=(factorial(n)/(factorial(n-k)*factorial(k)))*p^k*q^(n-k);
end
%x';

F=cumsum(x(2,:));
[x',F']

subplot(2,1,1);
stem(x(1,:),x(2,:));
subplot(2,1,2);
stairs(x(1,:),F);

a=35;
b=65;

sum(x(2,a+1:b+1));
F(b+1)-F(a);

a=40;
b=60;

sum(x(2,a+1:b+1));
F(b+1)-F(a);

a=45;
b=55;

sum(x(2,a+1:b+1));
F(b+1)-F(a);