Finding the Fourth Proportional to 15,265.98, 21,066.66 and 8,978.40

Step by Step Solution

1. Step 1: Write the proportion equation
   15,265.98 : 21,066.66 = 8,978.40 : x
2. Step 2: Convert to fraction form
   15,265.98/21,066.66 = 8,978.40/x
3. Step 3: Cross multiply
   15,265.98x = 21,066.66 × 8,978.40
4. Step 4: Simplify right side
   15,265.98x = 189,144,900.14
5. Step 5: Solve for x
   x = 189,144,900.14/15,265.98
6. Step 6: Final answer
   x = 12,389.96