Finding the Fourth Proportional to 10,985.80, 15,419 and 10,985.80

Step by Step Solution

1. Step 1: Write the proportion equation
   10,985.80 : 15,419 = 10,985.80 : x
2. Step 2: Convert to fraction form
   10,985.80/15,419 = 10,985.80/x
3. Step 3: Cross multiply
   10,985.80x = 15,419 × 10,985.80
4. Step 4: Simplify right side
   10,985.80x = 169,390,050.20
5. Step 5: Solve for x
   x = 169,390,050.20/10,985.80
6. Step 6: Final answer
   x = 15,419