Question 7 (20 points): Scenario 1: A salesperson introduces a mobile-data plan to Randy, which allows him to pay HKS800 per month and enjoy unlimited data usage. Randy said he is happy with the plan and 1s willing to subscribe to it. a) Explain the above Randy's decision by using a graph/graphs based on the concept of marginal utility/happiness, consumer surplus and marginal cost that we discussed in lectures. (5 points) Scenario 2: A salesperson introduces a mobile-data plan to Michael, which allows him to pay HKS$200 per month and enjoy 20G of data usage. Michael said he is happy with the plan and 1s willing to subscribe to it. Note that Michael will use more than 20G of data when it is free- of-charge. (5 points) b) Explain the above Michael's decision by using a graph/graphs based on the concept of marginal utility/happiness, consumer surplus and marginal cost that we discussed in lectures. (5 points)