The following data are the lifetimes (in hours) of 20 certain electrical components:
6278 3113 9350 5236 11584
12628 7725 8604 14266 6215
3212 9003 3523 12888 9460
13431 17809 2812 11825 2398
Find a point estimate and 90% confidence interval for the population lower quartile.
Can you explain how and why we do the following problem?