The probability of an attempt (1.00 - 0.05) = 95%.
Probability that DHS will fail a 100% interdiction (1.00 - 0.25) = 75%
Probability that they will attempt AND DHS will fail is the combination (0.95 * 0.75) = 71.25%.
The is using a micrometer to measure a t*rd. :-)
Back to work here.
Whups. Sorry. I'm a social studies teacher. Not a math teacher. I was constantly telling this to my daughter when she was in grade school (She's getting married in two weeks ~sigh~) and I would say: "Go talk to your grandfather, HE'S the nuclear physicist!"