A tourist wishes to catch a train in 1.2 hours, which is 115 km away. If she spends the first half-hour going 90km/h, how fast will she need to go to get to station on time?

100km/hr

Explanation:

From the problem statement we know that distance of the trip is 115km

Expected time for the trip = 1.2hrs

→ If she spends the first half-hour going 90km/hr,

    Here  time  = 0.5hr

              speed  = 90km/hr

 The distance covered;

    Distance covered   =  Speed x time

    Distance covered  = 90 x 0.5  = 45km

→The remaining distance will be:

        Total distance - distance covered

              115km  - 45km  = 70km

→ The remaining time;

      1.2hr - 0.5hr  = 0.7hr

 Speed  =  

  Insert the parameters and solve;

  Speed  =   = 100km/hr

For the remaining lap, the tourist must travel at a rate of 100km/hr to catch up.