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# Arithmetic and Geometric progressions HELP watch

1. can anyone help me with this questions please.

4. In a geometric progression the sum of the first 2 terms is 108 and the sum of the third and fouth is 12. Find the two possible values of the common ration and their corresponding first terms. 6 marks

6.A pump is used to extract air from a bottle. The first operation of the pump extracts 56cm cubed of air and subsequent extractions follow a geometric progression. The third operation of the pump extracts 31.5 cm cubed of air.

a) Determine the common ration of the geometric progression and calculate the total amount of air tht could be extracted from the bottle, if the pump were to extract air indefinitely. 5 marks

b) After how many operations of the pump does the total amount of air extracted from thr bottle first exceeds 220 cm cubed. 5 marks
2. What have you done so far?

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