ExpertsGlobal5
In a group of men and women, what is the average (arithmetic mean) weight of the entire group?
(1) Of everyone in the group, 3/7 are men and have an average weight of 175 pounds.
(2) Of everyone in the group, 4/7 are women and have an average weight of 140 pounds.
Explanation: Let the total number of people in the group be N.
Average weight of the entire group = (Sum of all the weights)/N.
We need to find whether the value of (Sum of all the weights)/N can be determined. Statement (1) Number of men in the group = (3/7)N
The sum of the weights of all men = Average weight of men x Number of men in the group
The sum of the weights of all men = 175 x (3/7)N
It is NOT possible to determine the exact average weight of the entire group using the given information.
Hence, Statement (1) is insufficient. Statement (2) Number of women in the group = (4/7)N
The sum of the weights of all women = Average weight of women x Number of women in the group
The sum of the weights of all women = 140 x (4/7)N
It is NOT possible to determine the exact average weight of the entire group using the given information.
Hence, Statement (2) is insufficient. As Statement (1) alone as well as Statement (2) alone is insufficient to answer the question, we need to now combine the two statements.
Statement (1) and Statement (2) combined Average weight of the entire group
= (Sum of all the weights)/N
= (Sum of the weights of all men + Sum of the weights of all women)/N
= [175 x (3/7)N + 140 x (4/7)N]/N
= [175 x (3/7) + 140 x (4/7)]
It is possible to determine the exact average weight of the entire group.
Hence, Statement (1) and Statement (2) combined are sufficient. C is the correct answer choice.