Answer to Question #82458 in Statistics and Probability for Ibrahim Abdi

Question

sample of 40 electric batteries gives a mean life span of 600 hrs with a standard deviation of 20 hours. Another sample of 50 electric batteries gives a mean lifespan of 520 hours with a standard deviation of 30 hours. If these two samples were combined and used in a given project simultaneously, determine the combined new mean for the larger sample and hence determine the combined or pulled standard deviation.