What is the average (arithmetic mean) height of the n people in a certain group?
(1) The average height of the n/3 tallest people in the group is 6 feet 2(1/2) inches, and the average height of the rest of the people in the group is 5 feet 10 inches.
(2) The sum of the heightsof the n people is 178 feet 9 inches.
Stmt1: Avg of n/3 people= 6feet 2(1/2) inches = n/3 * 6feet 2(1/2) inches
Avg of 2n/3 people = 5feet 10 inches = 2n /3*5feet 10 inches
If we add both above quantities and divide it by n we will get the avg since n will cancel out. So, sufficient.
Stmt2: if sum is given to calculate avg we have to divide it by n. But we dont know the value of n so insufficient.
Hence A is the answer
My debrief: done-and-dusted-730-q49-v40