GMAT Prep Question  Negative Correlation
This topic has expert replies
Hi everyone, I've tried my hand at this but I'm not understanding how question 2 can be confirmed as True. I tried plotting the points (# of selfcheckout unlimited on the Xaxis, average customer age on the yaxis) and I don't see any kind of correlation. Could someone please shed some light on this problem? Thanks so much
 Attachments

 [email protected]
 Legendary Member
 Posts: 2663
 Joined: 14 Jan 2015
 Location: Boston, MA
 Thanked: 1153 times
 Followed by:127 members
 GMAT Score:770
Think about it in terms of approximate averages:Poisson wrote:Hi everyone, I've tried my hand at this but I'm not understanding how question 2 can be confirmed as True. I tried plotting the points (# of selfcheckout unlimited on the Xaxis, average customer age on the yaxis) and I don't see any kind of correlation. Could someone please shed some light on this problem? Thanks so much
When there are 4 lanes, the average age is: 34.5, 32, and 42, for an average of about 36.
When there are 6 lanes, the average age is 28.4 and 34.6, for an average of about 31.
When there are 8 lanes, the average age is 29.9
As the number of lanes goes up, the average age (or the average of the average age) goes down, hence the negative correlation.