Question 1125829
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The average of all 7 people is the total weight of the original 6 people, plus the weight of the 7th person, all divided by 7.  Algebraically....<br>
{{{((6*173)+x)/7}}}<br>
The average weight is now 165; so solve the equation<br>
{{{((6*173)+x)/7 = 165}}}<br>
I'll let you finish....<br>
For problems like this involving an average of numbers that are "close" together, here is a different strategy for solving the problem that you might like to try.<br>
The original 6 people have an average weight of 173, which is 8 pounds more than the average of all 7 people.  So all together, the weight of those 6 people is 6*8=48 pounds over the 165 average.  That means the 7th person's weight must be 48 pounds below the 165 average.<br>
So the weight of the 7th person is 165-48 = 117 pounds.