Question 870416
p(correct) = .25,  n = 8
P(x ≤ 4 correct) = binomcdf(8, .25 , 4) = .9727  0r 97.27% chance
Above shows the Use of the TI Caclulator
One may use on-line calculators: recommend stattrek.com
0r one can obtain answer 'by hand'
{{{P (x)= highlight_green(nCx)(p^x)(q)^(n-x) }}} 
P(x ≤ 4 correct) = P(x=0) + P(x=1) + P(x=2) + P(x=3) + P(x = 4)
P(x=0) = {{{highlight_green(8C0)(.25^0)(.75)^(8) }}}  
P(x=1) = {{{highlight_green(8C1)(.25^1)(.75)^(7) }}}  
P(x=2) = {{{highlight_green(8C2)(.25^2)(.75)^(6) }}}  
P(x=3) = {{{highlight_green(8C3)(.25^3)(.75)^(5) }}}  
P(x=4) = {{{highlight_green(8C4)(.25^4)(.75)^(4) }}} 
for cumulative Probabilities, recommend Calculator