Question

PLEASE TELL ME THE TEXTBOOK PUBLISHER (Selina consice, goyal) FROM WHICH THE BELOW QUESTION WAS TAKEN FROM ... KINDLY HELP ME ! and please mention which class too...ANSWER IF U KNOW ONLY ................... A motorist travels A to B at a speed of 40km/hr and returns at speed of 60km/hr. His average speed will be?

Answer 1

Answer:

Use d = r*t

t = d/r

d = distance one way.

Total time = d/40 + d/60

Round trip avg = 2d%2Ft+=+2d%2F%28d%2F40+%2B+d%2F60%29

= 2%2F%281%2F40+%2B+1%2F60%29

= 2*40*60/(40+60)

= 48 km/hr

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Notice it's similar to parallel resistors and parallel flows.

Avg = 2*r1*r2/(r1 + r2)

Explanation:

hope it's help you

Answer 2

Answer:

Selina Publishers for class 7

Explanation:

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