A national study has determined that people who work full ti

A national study has determined that people who work full ti

A national study has determined that people who work full time average 43.4 hours worked per week. Assume that the number of house worked per week for those who work full time is normally distributed. Suppose 12% of these workers more than 48 hours. Based on this perecentage, what is the standard deviation of number of hours worked per week for those workers?