Finding the Fourth Proportional to 12,978.21, 19,464.58 and 4,658.70

Step by Step Solution

1. Step 1: Write the proportion equation
   12,978.21 : 19,464.58 = 4,658.70 : x
2. Step 2: Convert to fraction form
   12,978.21/19,464.58 = 4,658.70/x
3. Step 3: Cross multiply
   12,978.21x = 19,464.58 × 4,658.70
4. Step 4: Simplify right side
   12,978.21x = 90,679,638.85
5. Step 5: Solve for x
   x = 90,679,638.85/12,978.21
6. Step 6: Final answer
   x = 6,987.07