The length of AC is 3 times the length of CD n the figure. If B is the midpoint of AC, and the length of CD is 5, what is the length of BD ?
10
12.5
13.5
15
17.5
From the figure, it shows the length of BD is the sum of BC and CD. The length of CD is given value, which is 5. Now we have find the length of BC.
Since the length of AC is 3 times the length of CD , we can calculate the length AC first.
AC = 3CD = 3\times 5=15
Since point B is the midpoint of AC, then BC is the half of AC
BC = \dfrac{1}{2}AC = 7.5
Next, sum of both BC and CD yields the length of BD
BD = BC+CD = 12.5
Therefore, B is the correct answer