Answer
Coefficient of $x^{7}$ will be 330
Work Step by Step
We know by Binomial theorem
$(x+y)^{n}$ = C(n,0)$x^{n}$ + C(n,1)$x^{n-1}$$y^{1}$ ... + C(n,n)$y^{n}$
So for coefficient of $x^{7}$ in $(1+x)^{11}$ we have n=11, j=7
coefficient = C(11,7) = 330
