Answer:
Total of 39 beads are required to fill this necklace of 13 inch length.
Explanation:
Maggie is making a necklace using 13 inch string and identical beads.
Length of necklace = 13 inch
The 15 beads fill 5 inches of the string
Total beads used for filling 5 inches = 15

Number of beads required to fill 13 inch string = 13 x 3 = 39
Total of 39 beads are required to fill this necklace of 13 inch length.