Hi, I had this question in an exam and I couldn't find the answer! can someone help me plz !

The rule of thumb states that the normal approcimation to the binomial distribution is adequate if 0< p- 3 SQRT(pq/n) and p+ 3SQRT(pq/n) <1

a) show that p+ 3 SQRT(pq/n) < 1 if and only if n>9q/p

b) show that 0< p- 3 SQRT(pq/n) if and only if n> 9q/p


Thank you