A random study reported that 80% of very-low-birth-weight babies graduate from high school by age 20. If 280 very-low-birth-weight babies are followed through high school, how many would you expect to graduate from high school?

**Solution:-**

Recall that if a random variable x can take on the n values x_{1},x_{2}…..,x_{n } and the probabilities that these values occur are, respectively, p_{1},p_{2},….,p_{n}, then the expected of the random variable is E(x) = x_{1}p_{1}+x_{2}p_{2 }+ …..x_{n}p_{n.}

(0.80)(280) = 224

Therefore , it is expected that 224 out of 280 very-low-birth-weight babies will graduate high school by the age of 20.