Exercise

Invalid phone numbers

The customer support team is grateful for your work so far, but during their first day of calling participants, they ran into some phone numbers that were invalid. In this exercise, you'll remove any rows with invalid phone numbers so that these faulty numbers don't keep slowing the team down.

dplyr and stringr are loaded and sfo_survey is available.

Instructions

100 XP

Examine the invalid phone numbers by filtering for numbers whose length is not equal to 12.
Remove the rows with invalid numbers by filtering for numbers with a length of exactly 12.