Question

Adult IQ scores have a bell-shaped distribution with a mean of 100 and a standard deviation of 15. Use the Empirical Rule to find the percentage of adults with scores between 70 and 130.

Answer 1

\[z=\frac{x-\mu}{\sigma}=\frac{130-100}{15}=2\]\[\Phi(2)=0.9772\]\[0.9772-0.5=0.4772\]\[2\times0.4772=0.9544=95.44percent\]

Answer 2

I don't know what Empirical Rule means though.