In this exercise you will use $\mathrm{R}$ to compute the normal density and the cumulative distribution functions using dnorm and pnorm.

a. For any given values of mu, sigma, and y, what value does dnorm( $\mathrm{y}, \mathrm{mu}$, sigma) compute? Write the expression in terms of $\mu, \sigma$, and $y$. How does the value compare to the value computed by $1 /$ sigma*dnorm ( (y-mu)/sigma)? Explain.

b. For any given values of $\mathrm{mu}$, sigma, and $\mathrm{y}$, what value does pnorm(y, $\mathrm{mu}$, sigma) compute? Write the expression in terms of $\mu, \sigma$, and $y$. How does the value compare to the value computed by pnorm( (y-mu)/sigma)? Explain.