Finding the Fourth Proportional to 12,786.90, 19,155.78 and 7,842.12

Step by Step Solution

1. Step 1: Write the proportion equation
   12,786.90 : 19,155.78 = 7,842.12 : x
2. Step 2: Convert to fraction form
   12,786.90/19,155.78 = 7,842.12/x
3. Step 3: Cross multiply
   12,786.90x = 19,155.78 × 7,842.12
4. Step 4: Simplify right side
   12,786.90x = 150,221,925.45
5. Step 5: Solve for x
   x = 150,221,925.45/12,786.90
6. Step 6: Final answer
   x = 11,748.11