13.) A string of Christmas lights contains 20 lights. The lights are wired in series, so that if any light fails, the whole string will go dark. Each light has probability 0.98 of working for a 3-...

13.) A string of Christmas lights contains 20 lights. The lights are wired in series, so that if any  light fails, the whole string will go dark. Each light has probability 0.98 of working for a 3- year period. The lights fail independently of each other. Find the probability that the string  of lights will remain bright for 3 years.