You have an iPad and a laptop. You grab one (essentially at random), and are twice as likely to take the iPad rather than the laptop to school for the day. You also choose at random a device to do your HW on, but is three times more likely to be the laptop than the iPad. If you can't remember what device you did your HW on, what is the probability that you bring your HW to school? Make any reasonable assumptions to do the calculation.