Finding the Fourth Proportional to 9,979.64, 13,771.32 and 5,729.72

Step by Step Solution

1. Step 1: Write the proportion equation
   9,979.64 : 13,771.32 = 5,729.72 : x
2. Step 2: Convert to fraction form
   9,979.64/13,771.32 = 5,729.72/x
3. Step 3: Cross multiply
   9,979.64x = 13,771.32 × 5,729.72
4. Step 4: Simplify right side
   9,979.64x = 78,905,807.63
5. Step 5: Solve for x
   x = 78,905,807.63/9,979.64
6. Step 6: Final answer
   x = 7,906.68