Answer:
67 years old. (you only gave 4 people and missed out one person)
Explanation:
take all the ages first and put the unknown (age of the person who entered the room) as x.
14, 16, 16, 13, x
all of these numbers added to together would be:
59 + x
Because the question is talking about the mean age, to find mean:
add all the values in the data (ages) and divide by the total number of values on the list. (in your case would be 6 people (following your question) but you gave only 5 people including the x).
then (59 + x) / 6 = 21
21 x 6 = 126
126 = 59 + x
x = 67