Finding the Fourth Proportional to 9,978.87, 13,771.47 and 5,731.26

Step by Step Solution

1. Step 1: Write the proportion equation
   9,978.87 : 13,771.47 = 5,731.26 : x
2. Step 2: Convert to fraction form
   9,978.87/13,771.47 = 5,731.26/x
3. Step 3: Cross multiply
   9,978.87x = 13,771.47 × 5,731.26
4. Step 4: Simplify right side
   9,978.87x = 78,927,875.15
5. Step 5: Solve for x
   x = 78,927,875.15/9,978.87
6. Step 6: Final answer
   x = 7,909.50