Ian is organizing his books and putting them on shelves. He put 3 books on the first shelf, 5 books on the second shelf, 9 books on the third shelf, 15 books on the fourth shelf, and 23 books on the fifth shelf. If this pattern continues, how many books will Ian put on the sixth shelf?

Answer:33

Step-by-step explanation

The number of books increases by 2, when going from the first to the second shelf. i. e. 3+2=5

Then, when going from the second to the third shelf the number of books increses by 4. i. e. 5+4=9

From the third to the forth shelf the books increase by 6. i. e. 9+6 = 15

From the forth to the fifth books increase by 8. i. e. 15+8=23

Therefore from the fifth to the sixth shelf the number of books will increase by 10. i. e. 23+10 = 33