Finding the Fourth Proportional to 42,684.56, 64,021.21 and 13,099.91

Step by Step Solution

1. Step 1: Write the proportion equation
   42,684.56 : 64,021.21 = 13,099.91 : x
2. Step 2: Convert to fraction form
   42,684.56/64,021.21 = 13,099.91/x
3. Step 3: Cross multiply
   42,684.56x = 64,021.21 × 13,099.91
4. Step 4: Simplify right side
   42,684.56x = 838,672,216.39
5. Step 5: Solve for x
   x = 838,672,216.39/42,684.56
6. Step 6: Final answer
   x = 19,648.14