Finding the Fourth Proportional to 3,986.10, 5,978.46 and 1,212.10

Step by Step Solution

1. Step 1: Write the proportion equation
   3,986.10 : 5,978.46 = 1,212.10 : x
2. Step 2: Convert to fraction form
   3,986.10/5,978.46 = 1,212.10/x
3. Step 3: Cross multiply
   3,986.10x = 5,978.46 × 1,212.10
4. Step 4: Simplify right side
   3,986.10x = 7,246,491.37
5. Step 5: Solve for x
   x = 7,246,491.37/3,986.10
6. Step 6: Final answer
   x = 1,817.94