An arithmetic progression has 10 terms. The sum of the last five terms is 85. If the fourth term is 9, then find the sum of all 10 terms.
+1252 If the sum of the last 5 terms is 85, and there are 10 terms, then the eighth one is 17 (take 85/5).
And if the fourth term is 9, then the common difference is 2 (pretty simple math).
To find the sum, we just find the median and multiply it by the number of terms.
The median is 12, multiplied by 10, gets us 120.
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