Question

Suppose the cost of performing an experiment is $1000. If the experiment fails, an additional $300 occurs for certain
repairs before the next trial. Suppose the probability of a successful trial is 0.2, and that trials are independent. If trials
continue until a success,
a) what is the probability that it will take at least 3 attempts?
b) what is the expected cost?

Answer 1

at least three means
not zero
not one
not two
compute these, subtract the result from 1