What is your question that your asking?
A^2 +a-6. You use the method of foiling where you multiply the first two terms, the the outside terms, the inside terms, then the last terms. You would do a•a, then a•-2 the a•3 then 3•-2. You would get a^2 -2a +3a -6. Then combine like terms to get your answer.
Mean = 62 in
SD = 2 in
At 16% = 0.16 and using Z tables,
Z≈ -0.99
x =(-0.99*2) + 62 ≈ 60 in
This represents jockeys who are shorter than 60 in.