please help with part B.

A drwy that collected demographic data from uspondentsked them to categorize the annual incomes in thousands of dollars) to the group in the table to the right here! of respondents for each income group is shown in the table Complete parts a) and Number of Respondent 69 115 Income $20 to under 330 to under 540 to under $50 150 to under 5.000 under 570 24 36 a) Calculate the approximate werage income of the spondents The approximate agencome of the respondents is $40 thousand Round to one decimal place as needed) b) Calculate the approximate venance and standard deviation of the income of the respondents The approximate arance of the income of the respondents thosand Round to two decimal places as needed)