Question 1126513
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Four arithmetic means between 12 and -13 make 5 gaps (intervals).


Each interval is  {{{(12-(-13))/5}}} = {{{25/5}}} = 5 units long in the number line.


This value of 5 is the common difference of the arithmetic progression.


So the values are  -13; -13 + 5 = -8;  -8 + 5 = -3;  -3 + 5 = 2;  2 + 5 = 7  and finally  7 + 5 = 12.


<U>Answer</U>.  The four arithmetic means between 12 and -13  are  -8, -3, 2, and 7.
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Solved.