Finding the Fourth Proportional to 42,720.41, 64,070.76 and 12,728.54

Step by Step Solution

1. Step 1: Write the proportion equation
   42,720.41 : 64,070.76 = 12,728.54 : x
2. Step 2: Convert to fraction form
   42,720.41/64,070.76 = 12,728.54/x
3. Step 3: Cross multiply
   42,720.41x = 64,070.76 × 12,728.54
4. Step 4: Simplify right side
   42,720.41x = 815,527,231.49
5. Step 5: Solve for x
   x = 815,527,231.49/42,720.41
6. Step 6: Final answer
   x = 19,089.87