maths

A telecom company promptes a special offer on long distance call.In the first 30 minutes,the chande for calling Australia is $1/min.The next 30 minutes cost $0.6/min.The calling charge after one hour is $0.2/min.

1)For the following calling duration,find the average charge rate in $/min.
i)0.5 hour
ii)1 hour
iii)1.5 hours
iv)2 hours

2)Hence,what is the commercial strategy of the telecom company?

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要有steps thx