Question

Can someone please help me with this?​

Answer 1

Answer:

Let the d total distance be x km.

time taken to cover x/4 km = (x/4)/80

= x/320

Time taken to cover 3x/4 km = (3x/4)/60

= 3x/240.

Total time to cover the full distance

=x/320 + 3x/240 = (3x+12x)/960 = 15x/960 = x/64

So average speed = distance/time

= x/(x/64) = 64 km/hr.

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