Finding the Fourth Proportional to 13,091.40, 18,066.54 and 7,122.72

Step by Step Solution

1. Step 1: Write the proportion equation
   13,091.40 : 18,066.54 = 7,122.72 : x
2. Step 2: Convert to fraction form
   13,091.40/18,066.54 = 7,122.72/x
3. Step 3: Cross multiply
   13,091.40x = 18,066.54 × 7,122.72
4. Step 4: Simplify right side
   13,091.40x = 128,682,905.79
5. Step 5: Solve for x
   x = 128,682,905.79/13,091.40
6. Step 6: Final answer
   x = 9,829.58