Finding the Fourth Proportional to 28,139.16, 42,210.96 and 9,419.30

Step by Step Solution

1. Step 1: Write the proportion equation
   28,139.16 : 42,210.96 = 9,419.30 : x
2. Step 2: Convert to fraction form
   28,139.16/42,210.96 = 9,419.30/x
3. Step 3: Cross multiply
   28,139.16x = 42,210.96 × 9,419.30
4. Step 4: Simplify right side
   28,139.16x = 397,597,695.53
5. Step 5: Solve for x
   x = 397,597,695.53/28,139.16
6. Step 6: Final answer
   x = 14,129.69