Answer:
c) 81.5
Step-by-step explanation:
Listing the 25 ages in crescent order:
60 61 62 63 64 65 66 68 68 69 70 73 73 74 75 76 76 81 81 82 86 87 89 90 92
The upper or third quartile's position is given by:
[tex]Q_3=N_{\frac{3}{4}(n+1)}\\Q_3}=N_{\frac{3}{4}(25+1)}=N_{19.5}[/tex]
This means that the third quartile is the average between the 19th and 20th numbers:
[tex]Q_3=\frac{81+82}{2} \\Q_3 = 81.5[/tex]
The upper quartile is 81.5.