Detecting a computer virus attack. chance (winter 2004) presented basic methods for detecting virus attacks (e. g., trojan programs or worms) on a network computer that are sent from a remote host. these viruses reach the network through requests for communication (e. g., e-mail, web chat, or remote login) that are identified as "packets." for example, the "syn flood" virus ties up the network computer by "flooding" the network with multiple packets. cybersecurity experts can detect this type of virus attack if at least one packet is observed by a network sensor. assume the probability of observing a single packet sent from a new virus is only .001. if the virus actually sends 150 packets to a network computer, what is the probability that the virus is detected by the sensor?

An annual marathon covers a route that has a distance of approximately 26 miles. winning times for this marathon are all over 2 hours. the following data are the minutes over 2 hours for the winning male runners over two periods of 20 years each. earlier period 14 12 15 22 13 10 19 13 9 14 20 18 16 20 23 12 18 17 6 13 recent period 7 11 7 14 8 9 11 14 8 7 9 8 7 9 9 9 9 8 10 8 (a) make a stem-and-leaf display for the minutes over 2 hours of the winning times for the earlier period. use two lines per stem. (use the tens digit as the stem and the ones digit as the leaf. enter none in any unused answer blanks. for more details, view how to split a stem.) minutes beyond 2 hours earlier period 0 1 2 (b) make a stem-and-leaf display for the minutes over 2 hours of the winning times for the recent period. use two lines per stem. (use the tens digit as the stem and the ones digit as the leaf. enter none in any unused answer blanks.) minutes beyond 2 hours recent period (c) compare the two distributions. how many times under 15 minutes are in each distribution