GC content in Plasmodium falciparum genome is 20%. Assume that each base pair in the genome has equal probability of being GC. a. What is the probability of finding no AT pairs if 4 pairs were...

GC content in Plasmodium falciparum genome is 20%. Assume that each base pair in the genome has equal probability of being GC.
a. What is the probability of finding no AT pairs if 4 pairs were randomly chosen?
b. What is the probability of finding 2 or more AT pairs in 4 pairs?
c. What is the probability of finding an AT pair at the 4th base pair but not on the first three).