The Johnsons are moving to a different house in town. They are trying to estimate the cost of moving and find the least expensive option. The moving

company told them that if they hire a small truck and two movers, the cost of renting the small truck is a fixed $$200$ per day, and it will take two movers

nine hours to move all the items. The Johnsons will also need to get $3$ hours of after$-$school childcare at $$15$ per hour for each of their two kids. The cost

of each mover is $$25$ per hour with an extra meal allowance for $$10$ every four hours. If the Johnsons use a large truck with a fixed daily rate of $$500$

and hire three movers, then it will only take five hours to move. In addition, the Johnsons will avoid any after$-$school childcare costs.

a$.$ Construct an influence diagram for the decision model.

b$.$ Build a spreadsheet model based on the influence diagram to help the Johnsons decide which moving option is less expensive. What is the cost

saving if the Johnsons select the less expensive option?