Finding the Fourth Proportional to 21,530.28, 29,711.37 and 13,146.78

Step by Step Solution

1. Step 1: Write the proportion equation
   21,530.28 : 29,711.37 = 13,146.78 : x
2. Step 2: Convert to fraction form
   21,530.28/29,711.37 = 13,146.78/x
3. Step 3: Cross multiply
   21,530.28x = 29,711.37 × 13,146.78
4. Step 4: Simplify right side
   21,530.28x = 390,608,844.89
5. Step 5: Solve for x
   x = 390,608,844.89/21,530.28
6. Step 6: Final answer
   x = 18,142.30