Finding the Fourth Proportional to 28,442.16, 42,685.02 and 12,870.72

Step by Step Solution

1. Step 1: Write the proportion equation
   28,442.16 : 42,685.02 = 12,870.72 : x
2. Step 2: Convert to fraction form
   28,442.16/42,685.02 = 12,870.72/x
3. Step 3: Cross multiply
   28,442.16x = 42,685.02 × 12,870.72
4. Step 4: Simplify right side
   28,442.16x = 549,386,940.61
5. Step 5: Solve for x
   x = 549,386,940.61/28,442.16
6. Step 6: Final answer
   x = 19,315.94