The answer in this question is broadcast. Refer to curriculum topic: 5.1.3 On Ethernet networks, the broadcast MAC address is 48 binary ones displayed as hexadecimal FF-FF-FF-FF-FF-FF. So the hexadecimal address FF-FF-FF-FF-FF-FF represents broadcast the MAC address. The broadcast MAC address is a 48 binary.
Hope you can read my handwriting. the image cut off the right side, b = 1.009213324... but question asks to round to nearest thousandth so it's 1.009
For the second part just use the equation to find P when t = -1 and see if P is less than (underpredicts) the number from the question or greater than (overpredicts) the number. I haven't calculated it but I think it will be smaller and thus underpredicts just from looking at the numbers when t = -1