Assume we interested in relationship between the age of individual, as measured by visits. Suppose after selecting 15 members the observation:
Visits: 3 5 4 2 1 3 6 7 4 5 10 1 2 3 8
Age: 28 45 50 19 16 27 54 63 32 42 68 19 23 30 61
Use this data to find the Covariance between age and the number of visits.