800score.com http://www.800score.com/forum/ 

GMAT Statistics http://www.800score.com/forum/viewtopic.php?f=3&t=122 
Page 1 of 1 
Author:  questioner [ Wed Jan 26, 2011 5:29 pm ] 
Post subject:  GMAT Statistics 
A salesman's income consists of a commission and a base salary of $350 per week. Over the past 5 weeks, his weekly income totals have been $406, $413, $420, $436 and $395. What must his average (arithmetic mean) commission be per week over the next two weeks so that his average weekly income is $500 over the 7week period? A. $150 B. $245 C. $365 D. $715 E. $730 (C) We need to do this problem stepbystep. First, we add up the total income amounts for the past 5 weeks: $406 + $413 + $420 + $436 + $395 = $2070. To average $500 over 7 weeks, the salesman would need to earn: $500 × 7 = $3500. Subtract $2070 from $3500 to determine how much he would need to earn, in total, over the next 2 weeks to average $500 for the 7 weeks: $3500 – $2070 = $1430. Since he will earn $700 in base salary over the next two weeks, the commission he must earn in the next two weeks is: $1430 – $700 = $730. This is an average of $730/2 = $365 per week for these two weeks. The correct answer is choice (C).  Question Statemtn does not clarify the amount for Salary. It misleads the reader to believe that Commission + Salary is $350 instead of the just the base salary of $350. 
Author:  Gennadiy [ Wed Jan 26, 2011 5:35 pm ] 
Post subject:  Re: GMAT Statistics 
Any base salary is a fixed value, while any commission depends on the job results. It's the essence of a commission. Furthermore, the varying commission is clearly the reason for the total income to be $406, $413, $420, $436 and $395 over the 5 weeks. 
Page 1 of 1  All times are UTC  5 hours [ DST ] 
Powered by phpBB © 2000, 2002, 2005, 2007 phpBB Group http://www.phpbb.com/ 