Internet sites often vanish or move, so that references to them can't be followed. Supposed 13% of Internet sites referenced in major scientific journals are lost within two years after publication. If a paper contains five Internet references, what is the probability that all five are still good two years later

The probability that all five are still good two years later is 0.498.

Explanation:

Let X = number of internet sites that vanishes within 2 years.

The probability of an internet site vanishing within 2 years is: P (X) = p = 0.13.

A paper consists of n = 5 internet references.

The random variable X follows a Binomial distribution with parameters n = 5 and p = 0.13.

The probability mass function of a Binomial distribution is:

Compute the probability of X = 0 as follows:

Thus, the probability that all five are still good two years later is 0.498.