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This kind of problems requires to add the working velocities. The total velocity is the sum of the individual velocities.
Anita's velocity = 1 pool/8 hours
Chao's velocity = 1 pool/6 hours
Combined velocity 1/8 + 1/6 = (3 + 4)/24 = 7/24 pool/hour
Time = 1 pool / (7/24) pool/hour = 24/7 hour =3.43 hours
Answer:

Step-by-step explanation:
The given sequence is a geometric sequence.
We can find the common ratio using any two consecutive terms of the sequence.

The common ratio is 
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