Finding the Fourth Proportional to 42,810.88, 64,205.28 and 12,819.20

Step by Step Solution

1. Step 1: Write the proportion equation
   42,810.88 : 64,205.28 = 12,819.20 : x
2. Step 2: Convert to fraction form
   42,810.88/64,205.28 = 12,819.20/x
3. Step 3: Cross multiply
   42,810.88x = 64,205.28 × 12,819.20
4. Step 4: Simplify right side
   42,810.88x = 823,060,325.38
5. Step 5: Solve for x
   x = 823,060,325.38/42,810.88
6. Step 6: Final answer
   x = 19,225.49