Question

According to a recent article the average number of babies born with significant hearing loss (deafness) is approximately two per 1,000 babies in a healthy baby nursery. The number climbs to an average of 30 per 1,000 babies in an intensive care nursery. Suppose that 1,000 babies from healthy baby nurseries were randomly surveyed. Find the probability that exactly two babies were born deaf.

Answer 1

Answer:

0.27

Step-by-step explanation:

The probability P that exactly two babies were born deaf can be gotten by the binomial distribution as

$P = {n\choose k} \, p^k \,(1-p)^{n-k}$

where n is the sample size (the number of babies  randomly surveyed), k is the number of success, i. e., the baby is deaf; and p is the probability of selecting a deaf baby = 2/1000 = 0.002. Therefore

$P = {1000\choose 2}\, 0.002^2\, (1-0.002)^{1000-2}$

$P = 0.27$