Kelly is making a beaded bracelet with beads that measure 4 mm and 7.5 mm long. If the bracelet is 15 cm long and Kelly uses the same number of each type bead, about how many beads will she use?

Answer: 260.869 bead

In this case, Kelly will use the same number of each type bead. Then you must calculate the bead mean length. The calculation will be:

2 bead = 4mm + 7.5mm

2 bead = 11.5mm

1 bead = 5.75m

Then, divide the bracelet length with bead mean length

15cm x 100mm/cm / (5.75/bead) = 260.869 bead.