Finding the Fourth Proportional to 12,904.28, 17,817.94 and 9,915.40

Step by Step Solution

1. Step 1: Write the proportion equation
   12,904.28 : 17,817.94 = 9,915.40 : x
2. Step 2: Convert to fraction form
   12,904.28/17,817.94 = 9,915.40/x
3. Step 3: Cross multiply
   12,904.28x = 17,817.94 × 9,915.40
4. Step 4: Simplify right side
   12,904.28x = 176,672,002.28
5. Step 5: Solve for x
   x = 176,672,002.28/12,904.28
6. Step 6: Final answer
   x = 13,690.96