As a resident of Big City you feel the need to buy two large watchdogs. The dogs’ trainer asserts that each dog is 70% likely to detect and “discourage” any intruder.
a. Assuming each dog acts independently, how likely is it that an intruder would go undetected?
b. Still insecure, you are considering two additional measures:
(1) adding one more dog, identical to the others, or
(2) retraining the two original dogs, so that each would have a 90% probability of detecting an intruder. Which alternative would you recommend? Explain.