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[TheProphet]

Here's the info:
Tim and Rick both can run at speed v(r) and walk at speed v(w), with v(r) > v(w). They set off together on a journey of distance D. Rick walks half of the distance and runs the other half. Tim walks half of the time and runs the other half.
The total time = (D/2v(r))+(D/2v(w))

Here's the problem!

Find Rick's average speed for covering the distance D.
Express Rick's average speed v(a) in terms of v(r) and v(w)

Here's my solution:
Total distance = D and the time taken = (D/2v(r))+(D/2v(w)).
s=D/T
So v(a) =  D/(D/2v(r))+(D/2v(w))
which can also be written v(a) = D/(D/2)(v(r)+v(w))
v(a) = D/D/2 * 1/(v(r)+v(w))

2v(a) = D/D * 2/(v(r)+v(w))

2v(a) = 2/(v(r)+v(w))

v(a) = 1/(v(r)+v(w))

Is this correct?

[werty892]

Here's the info:
Tim and Rick both can run at speed v(r) and walk at speed v(w), with v(r) > v(w). They set off together on a journey of distance D. Rick walks half of the distance and runs the other half. Tim walks half of the time and runs the other half.
The total time = (D/2v(r))+(D/2v(w))

Here's the problem!

Find Rick's average speed for covering the distance D.
Express Rick's average speed v(a) in terms of v(r) and v(w)

Here's my solution:
Total distance = D and the time taken = (D/2v(r))+(D/2v(w)).
s=D/T
So v(a) =  D/(D/2v(r))+(D/2v(w))
which can also be written v(a) = D/(D/2)(v(r)+v(w))
v(a) = D/D/2 * 1/(v(r)+v(w))

2v(a) = D/D * 2/(v(r)+v(w))

2v(a) = 2/(v(r)+v(w))

v(a) = 1/(v(r)+v(w))

Is this correct?

Just saying, you may want the life advice boards, that's what there there for