In the midst of the Cold war, in the 1950s, a sleek aircraft known as the Avro Arrow was built to intercept Soviet bombers that might have entered North American air space over the North Pole. The Arrow was scrapped in 1959 and the planes were ordered to be destroyed. Ninemodel aircrafts were launched into Lake Ontario and were never recovered.

In the summer of 2017,a mission to recover the ninemodels of the Avro Arrow was launched. It wasa collaborative effort by severalprivate companies in collaboration with the Canadian Coast Guard and the Royal Canadian Military Institute.

A Newfoundland company,KrakenSonar Systems, was awarded the $500,000 contract which will involve deploying its state-of-the-artThunderFish underwater vehicleandAquaPixsonar systemto capture high-quality images of the lake bed.

The high probability area that was to be searched included 64 square km.

The Thunderfish and crew can map and analyse 1 square km at a time, doing 5 in a week. Assume each of the 9 model Avro Arrows would occupy it's own square km. Meaning, there cannot be twoArrows in the same square km.

What is the probability that, after the first week, the crew find at least one of the Avro Arrows?

Source

Note: The information about how much the crew can analyse at one time and the fact that only 1 Arrow is in the same square km has been made up for the purpose of the question.

How would i answer this question using the combination/permutation formula?