PLEASE HELP

What is the value of n in this equation?

The frequency table shows a set of data collected by a doctor for adult patients who were diagnosed with a strain of influenza. patients with influenza age range number of sick patients 25 to 29 30 to 34 35 to 39 40 to 45 which dot plot could represent the same data as the frequency table? patients with flu

3.4a=57.8 what is the the value of a

What unit of been sure would be appropriate for the volume of a sphere with a radius of 2 meters