Tim Cook answered
To discover what letter follows in the sequence E, I, and L, we need to take a look at the alphabet.
Sequences Can Show How Smart You Are!
A letter sequence question such as this one tests your ability to think logically and analytically. Some employers use similar tests as part of their selection procedures and this test will give you some idea of what to expect. Letter patterns are also used in IQ tests. If you fancy trying a few more yourself, take a test here. To learn more about number sequences, watch this video: