Plzz answer it asap

Plzz answer it asap {Mean = 412} me marks obtained by 90 students in a certain examinatjon. Calculate the etudergt step deviatjon method. 10-21) 7 20-30 13 30-40 40-50 60-70 70--80 80-90 20 25 10 8 6 {Moan = 42.89 marks)