Question 1164237
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I will let you have the pleasure of doing the calculations yourself....<br>
(1) Find the 6 terms of the geometric progression.  A calculator should make it easy; or an excel spreadsheet.  Or you might be able to do it with mental arithmetic.<br>
(2) Find the sum of those 6 terms.<br>
(3) Divide that sum by the number of terms in the arithmetic progression, 21.  That will give you the average of all the terms in the arithmetic progression.<br>
(4) In an arithmetic progression of 21 terms the 11th term is the average of all the terms.  So you know the 11th term.<br>
(5) Add 10 times the common difference to the 11th term to find the 21st (last) term; subtract 10 time the common difference from the 11th term to find the first term.<br>