The ages of students at a university are normally distributed with a mean of 21. What percentage of the student body is at least 21 years old?.

4+6x-3x^3 in standard form with explanations because i don’t understand

Simplify 6sin θsec θ. choices a) 6 tan θ b) 6 cos θ c) 6 cot θ d) 6

Bismuth-210 is an isotope that radioactively decays by about 13% each day, meaning 13% of the remaining bismuth-210 transforms into another atom (polonium-210 in this case) each day. if you begin with 233 mg of bismuth-210, how much remains after 8 days?