Final answer:
The monthly cost of T-Mobile's Jump! On Demand program can range from $10 to $30 for the phone lease, with an additional cost for the monthly service plan.
Step-by-step explanation:
The monthly cost of T-Mobile's Jump! On Demand program varies depending on the phone you choose. With Jump! On Demand, you have the option to lease a phone rather than buying it outright. The cost of leasing a phone can range from $10 to $30 per month. However, keep in mind that this cost only covers the phone itself, and you will also need to pay for a monthly service plan, which can range from $40 to $100 depending on the plan you choose.