Question :
How many tosses of a fair coin are needed so that the probability of getting atleast one head is 0.875?
Mr fantastic i still dont know how should i find 'n'
using Binomial
$\displaystyle p(x,n,\theta)$ = $\displaystyle \binom{n}{x} \theta^x (1- \theta)^{n-x}$
$\displaystyle p(0,n,0.5)$ = $\displaystyle \binom{n}{0} (0.125)^0 (0.875)^{n}$............Is this what u meant by substituting in the usual Binomial formula