There are 100 students in Form V. All students study Mathematics; 20 students study Physics; 36 students study Chemistry; 41 students study Biology; 5 students study Physics, Chemistry and Mathematics only; 3 students study Phys- ics, Biology and Mathematics only; 15 students study Chemistry, Biology and Mathematics only; 4 students study all four subjects. (a) Draw a carefully labelled Venn diagram to represent the data, using the universal set as the set of students who study Mathematics. (b) Determine the number of students who study at least two subjects.​