1)p=0.3
q=1-0.3=0.7
P(x=0)=C5,0*p0q5-0=1*1*0.75=0.16807
P(x=1)=C5,1*p1q4=1*1*0.75=0.36015
P(x=2)=C5,2*p2q3=1*1*0.75=0.3087
P(x=3)=C5,3*p3q2=1*1*0.75=0.1323
P(x=4)=C5,4*p4q1=1*1*0.75=0.02835
P(x=5)=C5,5*p5q0=1*1*0.75=0.00243
Number of sales Probability
0 0.16807
1 0.36015
2 0.3087
3 0.1323
4 0.02835
5 0.00243
2)E(x)=0*0.16807+1*0.36015+2*0.3087+3*0.1323+4*0.02835+5*0.00243=1.5, round to 2.
variance=npq=5*0.3*0.7=1.05
3)P(x≤2)=P(x=0)+P(x=1)+P(x=2)=0.83692
4)there cannot be 6 sales
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