You are to drive to an interview in another town, at a distance of 340 km on an

Question

You are to drive to an interview in another town, at a distance of 340 km on an expressway. The interview is at 11:15 a.m. You plan to drive at 100 km/h, so you leave at 8:00 a.m. to allow some extra time. You drive at that speed for the first 100 km, but then construction work forces you to slow to 42.0 km/h for 41.0 km. What would be the least speed (in km/h) needed for the rest of the trip to arrive in time for the interview?
I had guessed 100.708 km but it was incorrect.
Any help would be appreciated.
:)

Explanation / Answer

so we have doen 100km at 100km/h which is 1 hour
and 41km/h for 42 km which is 61.46 mins
so we have used 2:1.46 and have 1:13.54 mins left to travel 148 km
using the formula speed = distance divided by time we can assume:
S = 148 / 1.22566 (time in a decimal form)
S=120.75km/h

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