Finding the Fourth Proportional to 10,488.78, 15,718.48 and 5,218.80

Step by Step Solution

1. Step 1: Write the proportion equation
   10,488.78 : 15,718.48 = 5,218.80 : x
2. Step 2: Convert to fraction form
   10,488.78/15,718.48 = 5,218.80/x
3. Step 3: Cross multiply
   10,488.78x = 15,718.48 × 5,218.80
4. Step 4: Simplify right side
   10,488.78x = 82,031,498.74
5. Step 5: Solve for x
   x = 82,031,498.74/10,488.78
6. Step 6: Final answer
   x = 7,820.88