Answer:
To met both conditions, the smallest sample size n should be 50.
Step-by-step explanation:
To test a claim about proportion there are two requirements that must be met:
1) The sample observations are a simple random sample
2) The conditions for a binomial distribution are satisfied, that is:

In this case, p=0.1, so first we have:

Second,

To met both conditions, the smallest sample size n should be 50.