Please assist with question 1

DV SECTION 1 [20] You have been appointed as the intern at NAB Bank and you are required to conduct a study to assess how many hours managers spend in meetings in a week. There have been complaints that meetings take up too much of their time. You have selected 20 senior managers in your study. The following numbers of hours were spent in meetings in the past week: Number of hours Number of managers (frequency) (1-5) 1 (6-10) 2 (11-15) 4 (16-20) (21-25) (26-30) 1. Calculate the mean of the grouped data. (3)