Finding the Fourth Proportional to 5,211.81, 7,820.46 and 3,987.09

Step by Step Solution

1. Step 1: Write the proportion equation
   5,211.81 : 7,820.46 = 3,987.09 : x
2. Step 2: Convert to fraction form
   5,211.81/7,820.46 = 3,987.09/x
3. Step 3: Cross multiply
   5,211.81x = 7,820.46 × 3,987.09
4. Step 4: Simplify right side
   5,211.81x = 31,180,877.86
5. Step 5: Solve for x
   x = 31,180,877.86/5,211.81
6. Step 6: Final answer
   x = 5,982.73