Number of Middle Terms

Q. If the three consecutive coefficient in the expansion of $(1+x{)}^n$ are $28,56$ and $70,$ then the value of $n$ is

Q. If the coefficients of three consecutive terms in the expansion of ${(1+x)}^n$ are in the ratio of 1:7:42 then n is divisible by

1. 9
2. 5
3. 3
4. 11