As in Exercises 10.2 and 11.2, four students order noodles at a certain local restaurant. Their orders

Question:

As in Exercises 10.2 and 11.2, four students order noodles at a certain local restaurant. Their orders are placed independently. Each student is known to prefer Japanese pan noodles 40% of the time. Let X be the number of students who order Japanese pan noodles. What is the variance of X?