Finding the Fourth Proportional to 12,978.28, 17,910.50 and 7,236.25

Step by Step Solution

1. Step 1: Write the proportion equation
   12,978.28 : 17,910.50 = 7,236.25 : x
2. Step 2: Convert to fraction form
   12,978.28/17,910.50 = 7,236.25/x
3. Step 3: Cross multiply
   12,978.28x = 17,910.50 × 7,236.25
4. Step 4: Simplify right side
   12,978.28x = 129,604,855.63
5. Step 5: Solve for x
   x = 129,604,855.63/12,978.28
6. Step 6: Final answer
   x = 9,986.29