<PRE><B>Question 894813</B>
1)An embroidery pattern calls for five stitches in the first row and for three more stitches in each successive row. The 25th row, which is the last row, has 77 stitches. Find the total number of stitches in the pattern.


An = A1 + (n-1)*d


Sn = n*(A1 + An)/2


A1 = 5
d = 3


A25 = 5 + 24*3 = 77


S25 = 25*(5+77)/2 = 25*(82)/2 = 25*41 = 1025
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