Finding the Fourth Proportional to 13,685.96, 18,887.72 and 7,718.18

Step by Step Solution

1. Step 1: Write the proportion equation
   13,685.96 : 18,887.72 = 7,718.18 : x
2. Step 2: Convert to fraction form
   13,685.96/18,887.72 = 7,718.18/x
3. Step 3: Cross multiply
   13,685.96x = 18,887.72 × 7,718.18
4. Step 4: Simplify right side
   13,685.96x = 145,778,784.16
5. Step 5: Solve for x
   x = 145,778,784.16/13,685.96
6. Step 6: Final answer
   x = 10,651.71