Finding the Fourth Proportional to 9,920.81, 13,690.71 and 5,671.96

Step by Step Solution

1. Step 1: Write the proportion equation
   9,920.81 : 13,690.71 = 5,671.96 : x
2. Step 2: Convert to fraction form
   9,920.81/13,690.71 = 5,671.96/x
3. Step 3: Cross multiply
   9,920.81x = 13,690.71 × 5,671.96
4. Step 4: Simplify right side
   9,920.81x = 77,653,159.49
5. Step 5: Solve for x
   x = 77,653,159.49/9,920.81
6. Step 6: Final answer
   x = 7,827.30