Answer:
1.66479*10^(-6)
Step-by-step explanation:
to get 70% correct question out of 20 the student have correct 14 questions correct.
probability of getting answer correct p= 1/5=0.2
probability of getting answer wrong q= 4/5=0.8
its case of binomial distribution where
n= 20, r= 14 , p= 0.2 and q= 0.8
therefore
[tex]_{20}^{14}\textrm{C}\times 0.2^{14}\times0.8^{6}[\tex]
solving we get
1.66479*10^(-6)