# Exercise - Simulating the Bivariate Normal Distribution

Write an R function called `rbinorm()`

that uses `rnorm()`

to generate draws from a *bivariate*, i.e. two-dimensional, normal distribution. Your function should take three arguments: `n_draws`

is the number of simulation draws, `mean_vec`

is a vector of length two specifying the mean of each component, and `var_mat`

is a \((2\times 2)\) variance-covariance matrix. Read the documentation for the R function `stopifnot()`

and use it to throw an error if `var`

is not positive definite. Your function should return an `nreps`

by `2`

matrix containing the desired draws. You may *not* use function `chol()`

: I want you to do everything “by hand.” Check your work by drawing a large number of simulations, calculating the sample means and variance-covariance matrices, and plotting the marginal and joint distribution.