Carefully read Scenario 1 below and answer questions 11-14 which follow.

Scenario 1: A team of Epidemic Intelligence Service officers from the CDC arrives in Rhode Island to assist the state health department with investigation and control of an outbreak of measles.The team is asked to include the entire state in the investigation; thus, a confirmed case of measles in this outbreak is any resident of Rhode Island with an illness clinically compatible with measles who either has a positive laboratory test for measles or is a contact of someone with a positive test.Individuals with clinically compatible illnesses who did not have laboratory confirmation and were not contacts were classified as "possible cases". (No recovery date would mean that the individual is still sick, or did not recover during the time frame of interest.No lab or contact is a non-confirmed case and these are considered the "possible cases".These cases are not included depending on the question being asked, specifically prevalence & incidence, because they are not confirmed with the illness.) The team members arrive in Rhode Island on March 1^st and spent a month investigating.They found case information as detailed in the chart below.

Case # RI resident Onset date Recovery date Lab confirmed Contact Yes 2/4/2015 2/19/2015 X No 2/18/2015 2/22/2015 X Yes 2/18/2015 3/2/2015 X No 2/18/2015 3/2/2015 X Yes 2/19/2015 3/6/2015 X No 2/20/2015 2/27/2015 X 7 Yes 2/20/2015 3/6/2015 X Yes 2/20/2015 3/9/2015 X Yes 2/23/2015 3/9/2015 X 10 Yes 2/23/2015 3/10/2015 X 11 Yes 2/23/2015 3/15/2015 X 12 Yes 2/23/2015 3/29/2015 X 13 No 2/24/2015 3/29/2015 X 14 yes 3/7/2015 3/18/2015 X 15 yes 3/7/2015 3/19/2015 X 16 yes 3/7/2015 3/19/2015 X 17 yes 3/7/2015 3/20/2015 X 18 yes 3/7/2015 3/29/2015 X 19 yes 3/7/2015 4/1/2015 X 20 yes 3/8/2015 3/17/2015 X 21 yes 3/8/2015 3/22/2015 X 22 yes 3/9/2015 3/22/2015 X 23 yes 3/11/2015 3/29/2015 X 24 yes 3/11/2015 3/29/2015 X 25 yes 3/16/2015 3/29/2015 X 26 yes 3/17/2015 3/29/2015 27 yes 3/18/2015 3/29/2015 X 28 yes 3/21/2015 3/29/2015 X 29 yes 3/21/2015 3/29/2015 X 30 yes 3/21/2015 3/29/2015 X 31 yes 3/21/2015 3/29/2015 X 32 yes 3/21/2015 4/1/2015 X 33 yes 3/21/2015 4/2/2015 X 34 yes 3/21/2015 4/2/2015 X 35 yes 3/21/2015 4/2/2015 X 36 yes 3/21/2015 4/2/2015 37 yes 3/21/2015 38 yes 3/21/2015 39 yes 3/22/2015 40 yes 3/23/2015 41 yes 3/23/2015 42 yes 3/29/2015 43 yes 3/29/2015 44 yes 3/29/2015