Finding the Fourth Proportional to 13,516.42, 18,665.48 and 12,780.12

Step by Step Solution

1. Step 1: Write the proportion equation
   13,516.42 : 18,665.48 = 12,780.12 : x
2. Step 2: Convert to fraction form
   13,516.42/18,665.48 = 12,780.12/x
3. Step 3: Cross multiply
   13,516.42x = 18,665.48 × 12,780.12
4. Step 4: Simplify right side
   13,516.42x = 238,547,074.26
5. Step 5: Solve for x
   x = 238,547,074.26/13,516.42
6. Step 6: Final answer
   x = 17,648.69