diff --git a/README.md b/README.md
index e354bda..ef682fc 100644
--- a/README.md
+++ b/README.md
@@ -2,3 +2,30 @@
 
 # Answer to Homework Question
 I hope to learn how to perform MATLAB functions more easily.
+
+#Problem 4
+```MATLAB
+data=dlmread('US_energy_by_sector.csv',',',2,0);
+figure(1)
+plot(data(:,1),data(:,3),data(:,1),data(:,9));
+set(0, 'defaultAxesFontSize', 16)
+set(0,'defaultTextFontSize',14)
+set(0,'defaultLineLineWidth',3)
+set(gcf, 'Position', [200, 200, 1000, 800])
+xlabel('Time (years)')
+ylabel('Total Energy Consumed (trillions of BTUs)')
+legend('Residential','Transportation','Location','northwest')
+title('US Energy Consumption from 1949 to 2016')
+
+
+rescum=cumsum(data(:,3))./1000000;%cumulative sum of residential energy
+%consumption in quintillions
+transcum=cumsum(data(:,9))./1000000;%cumulative sum of transportational
+%energy consumption in quintillions
+figure(2)
+plot(data(:,1),rescum,data(:,1),transcum)
+set(gcf, 'Position', [500, 200, 1000, 800])
+xlabel('Time (years)')
+ylabel('Total Energy Consumed (quintillions of BTUs)')
+legend('Residential','Transportation','Location','northwest')
+title('Cumulative US Energy Consumption from 1949 to 2016')