Arcs and angles relay puzzle question

2,10,-50 next two numbers geometric sequence

Atown recently dismissed 5 employees in order to meet their new budget reductions. the town had 5 employees over 50 years of age and 19 under 50. if the dismissed employees were selected at random, what is the probability that exactly 2 employees were over 50? express your answer as a fraction or a decimal number rounded to four decimal places.

Me with these questions , i don’t understand scientific notation!