A certain elevator has a safe weight limit of 2,500 pounds. What is the greatest possible number of people who can safely ride on the elevator at one time with the average (arithmetic mean) weight of half the riders being 180 pounds and the average weight of the others being 230 pounds?  Choose the correct choice from the following choices: A) 7 B) 8 C) 9 D) 10 E) 12
Lets assume there are 2X people.   Half of them have average weight of 180 and other half has 230.   Maximum Weight is = 2500   So 180*X + 230*X = 2500   =&gt; 410X = 2500   =&gt; X is approximately equal to 6.   So total people is  2*6= 
<gadget id="calculator"> 2*6</gadget>
<output>12</output>
12   Answer 12.
<result>E</result>
A certain elevator has a safe weight limit of 2,500 pounds. What is the greatest possible number of people who can safely ride on the elevator at one time with the average (arithmetic mean) weight of half the riders being 180 pounds and the average weight of the others being 230 pounds?