Step 1 :The problem is asking for the amount of time spent running where Routine #1 burns fewer calories than Routine #2. This can be represented as an inequality where the total calories burned in Routine #1 is less than the total calories burned in Routine #2.
Step 2 :In Routine #1, Justin burns 25 calories walking and 10.5 calories per minute running. So, the total calories burned in Routine #1 can be represented as \(25 + 10.5t\).
Step 3 :In Routine #2, Justin burns 46 calories walking and 6.3 calories per minute running. So, the total calories burned in Routine #2 can be represented as \(46 + 6.3t\).
Step 4 :The inequality to solve is therefore \(25 + 10.5t < 46 + 6.3t\).
Step 5 :Solving the inequality gives \(t < 5.0\). This means that for amounts of time spent running less than 5 minutes, Routine #1 will burn fewer calories than Routine #2.
Step 6 :Final Answer: \(\boxed{t < 5.0}\)