Part 2.
He wants to make a different array with the same nuber of dots (30 dots).
He can make an array with a number of rows that are multiples of 30: 2, 3, 5, 6, 10 and 15.
Then, he can use an array with 3 rows and an array of 10 rows, but he can not use an array with 4 rows.
Then, the solution is:
an array with 3 rows: Yes
an array with 4 rows: No
an array with 10 rows: Yes