Answer:
She need to buy 8 boards.
Step-by-step explanation:
Given:
Number of shelves = 30
Length of each shelf = 3 ft 9 inches
Length of each board she can buy = [tex]13\frac{1}{2}\ ft[/tex]
Now, using Unitary method, finding the total length of the 30 shelves.
Length of 1 shelf = 3 ft 9 in = [tex]3 + \frac{9}{12}=3+0.75=3.75\ ft[/tex]
∴ Length of 30 shelves = [tex]30\times 3.75=112.5\ ft[/tex]
Now, the number of boards that she can buy is given by dividing the total length of the shelves and length of each board. Thus,
Number of boards = [tex]\frac{\textrm{Total length of shelves}}{\textrm{Length of each board}}[/tex]
Number of boards = [tex]\frac{112.5}{13.5}=8.33\approx8[/tex]
Therefore, the number of boards she can buy are 8.
