An investigator wants to show that first-born children score higher on iq tests than second-borns. he takes a simple random sample of 400 two-child families in a school district, both children being enrolled in elementary school. he gives these children the wisc vocabulary test, with following results: the 400 first-borns average 29 and their sd is 10. the 400 second-borns average 28 and their sd is 10. does the result support the research hypothesis?

Assume that there is a 11% rate of disk drive failure in a year. a. if all your computer data is stored on a hard disk drive with a copy stored on a second hard disk drive, what is the probability that during a year, you can avoid catastrophe with at least one working drive? b. if copies of all your computer data are stored on four independent hard disk drives, what is the probability that during a year, you can avoid catastrophe with at least one working drive?