36 (probability that he/she stayed on the r first full-time job for less than one year)x >= 5 (out of 15 how many)P( x>=5) = P(x=5)+P(x=6)+.....+P(x=15)P(x=k) = 15Ck (0.......
= 1 - P[less than four] = 1 - {p(0) + p(1) +.....+p(4)}
Please find this.
b.
The expected number is E(X) = np = 30*0.36 = 10.8 = 11 (approximately)