Finding the Fourth Proportional to 42,818.88, 64,234.38 and 13,239.30

Step by Step Solution

1. Step 1: Write the proportion equation
   42,818.88 : 64,234.38 = 13,239.30 : x
2. Step 2: Convert to fraction form
   42,818.88/64,234.38 = 13,239.30/x
3. Step 3: Cross multiply
   42,818.88x = 64,234.38 × 13,239.30
4. Step 4: Simplify right side
   42,818.88x = 850,418,227.13
5. Step 5: Solve for x
   x = 850,418,227.13/42,818.88
6. Step 6: Final answer
   x = 19,860.82