The length of the fifth piece is 2 3/4 inches.
Given:
1st piece of wood = 1 1/2 inches
2nd piece of wood = 1 13/16 inches
3rd piece of wood = 2 1/8 inches
f(n) = 1st term + common difference(n-1)
To get the common difference, we need to deduct the fraction from its preceding fraction.
1st piece: 1 1/2 = (2*1 + 1)/2 = 3/2
2nd piece: 1 13/16 = (16*1+13)/16 = 29/16
3rd piece: 2 1/8 = (8*2+1)/8 = 17/8
29/16 - 3/2 = 29/16 - (3/2 * 8/8) = 29/16 - 24/16 = (29-24)/16 = 5/16
17/8 - 29/16 = (17/8 *2/2) - 29/16 = 34/16 - 29/16 = (34-29)/16 = 5/16
Find: 5th piece's measurement
1st term : 1 1/2 or 3/2
common difference : 5/16
f(5) = 3/2 + 5/16 (5-1)
= 3/2 + 5/16 (4)
= 3/2 + (5*4)/16
= 3/2 + 20/16
= (3/2 * 8/8) + 20/16
= 24/16 + 20/16
= (24 + 20)/16
f(5) = 44/16
f(5) = 2 12/16 simplified to 2 3/4 inches.
