There are 6 people in the elevator. Their average weight is 156 lbs. Another person enters the elevator, and increases the average weight to 151 lbs. What is the weight of the 7th person.  Select
A) 121  B) 168  C) 189  D) 190  E) 200

Rationale: solution average of 7 people after the last one enters = 151 . â ˆ ´ required weight = ( 7 x 151 ) - ( 6 x 156 ) = 1057 - 936 = 121 . answer a
Answer: A