A museum surveyed three groups of 5 members to find out how many times the members visited the museum in the past year. This table shows the results of the three samples. Survey Visits to the Museum
Group 1 {4, 10, 6, 3, 8}
Group 2 {3, 1, 2, 1, 2}
Group 3 {7, 9, 3, 4, 7}
Identify any surveys that are likely biased. Based on the unbiased surveys, estimate the mean number of visits per member in the past year.

Enter your answer in the box. Round to the nearest whole number.