The quality controller in a given firm had an accurate record of all the iron bars produced in May 1997. The following data shows those records Bar lengths (cm) No. of bars(f) for grouped data for ungrouped data, and For ungrouped data, and, For grouped data LILLIAN MUIRURI HSMU 314 5 201 – 250 25 251 – 300 36 301 – 350 49 351 – 400 80 401 – 450 51 Calculate the standard deviation of the lengths of the bars