To qualify for the finals in a racing event, a race car must achieve an average speed of 250 km/h on a track with a total length of 1600 m. If a particular car covers the first half of the track at an average speed of 230 km/h, what minimum average must it have in the second half of the event to qualify?

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Find the time it takes to cover 1600 m at 250 km/h.

Fine the time it takes to cover half that distance at 230 km/h.

Hence, find the time remaining to cover the other half distance left.

From that distance and the time remaining, you can now get the average speed required.