please use matlab

b. Find the 76% confidence interval for the average reflected light value of all red marbles. Question & Write a MATLAB script below that will generate a SINGLE figure containing three lines ON THE SAME FIGURE given that The data is stored in a file called PlotData.txt' The 1t column contains the x variable and the next 3 columns contain the y1, y2 and y variables Include appropriate axes labels, a chart title and a legend . Question 9 Write a MATLAB script below that will generate a SINGLE figure containing three SUBPLOTS of sin(x), cosx), and tan(x) from -pi to pi, in I row by 3 columns format. Include appropriate axes labels and chart titles. Using the polyfit and polyval functions, writes a MATLAB FUNCTION called "RegTest!" that takes in as input an array of x values, an array of y values, performs a quadratic and cubic fit on the data and suggests the optimal regression model based on the MSE. The following lines of code will calculate the MSE for you. e y- yfit: MSE = mean (e."2); Execution of your script should look like this >> RegTest0ol(x, y) The MSE of the quadratic regression is 0.025697 The MSE of the cubic regression is 0.0815 The optimal regression is quadratic