What is the probability rule for deciding whether events a and b are independent?

What is the smallest integer n such that n\sqrt{2} is greater than 20

Given: △abc, ab=15, bd=9 ad ⊥ bc , m∠c=30°. find: the perimeter of the triangle.

Naomi’s parents want to have 50,000, saved for her college education, if they invest 20000 today and earn 7% interest compound annually, about how long will it take them to save 50 thousand