R Exercises | Programming Exercises for Finance in the R Language

Math and Stats: Exercises

9. Approximating the normal distribution. A draw from the normal distribution can be approximated by summing draws from uniform distributions and then subtracting the expected value. Using the function runif(n, min, max), draw 25 observations from a uniform distribution with a minimum of 0 and a maximum of 1. Repeat this three times and then subtract the expectation, which is 1.5. Plot a histogram of your draws using hist().



                            # Draw observations from uniform distribution three times.
                            draws_1 <- runif(___, 0, ___)
                            draws_2 <- ___(___, ___, 1)
                            draws_3 <- ___

                            # Sum the draws and subtract the expectation.
                            approx_normal_draws <- ___

                            # Plot histogram of observations.
                            ___



                            # Draw observations from uniform distribution three times.
                            draws_1 <- runif(25, 0, 1)
                            draws_2 <- runif(25, 0, 1)
                            draws_3 <- runif(25, 0, 1)

                            # Sum the draws and subtract the expectation.
                            approx_normal_draws <- draws_1 + draws_2 + draws_3 - 1.5

                            # Plot histogram of observations.
                            hist(approx_normal_draws)


                            test_error()
                            test_function("runif", incorrect_msg="Did you use the `runif()` function?")
                            test_function("hist", incorrect_msg="Did you use `hist()` to plot a histogram?")
                            success_msg("Excellent work. Does your distribution appear to approximate a normal distribution well? Try increasing the number of draws.")

Did you set the parameters of the runif() correctly?

Previous Exercise Next Exercise