The following is all possible combinations Y means yes worker met requirement. N means No worker did not meet requirement. Green means bonus is given, red means no bonus given.

YY

YN

NY

NN

As you can see the only possibility that the worker does not receive the bonus is NN. It is much easier to calculate the probability of NN and then subtracting that probability from 1 in order to get the answer to the question.

The probability of NN

subtract that from 1 and you have the probability that the worker will meet the bonus requirement.