Answer:
If the Jones family needs to reach their destination by 1:15 PM and their drive will take one and a half hours, we can work backwards to determine the latest time they can leave.
Subtracting 1.5 hours from 1:15 PM, we get:
1:15 PM - 1.5 hours = 11:45 AM
Therefore, the latest time the Jones family can leave and still reach their destination on time is 11:45 AM.