Finding the Fourth Proportional to 42,728.29, 64,115.42 and 17,785.55

Step by Step Solution

1. Step 1: Write the proportion equation
   42,728.29 : 64,115.42 = 17,785.55 : x
2. Step 2: Convert to fraction form
   42,728.29/64,115.42 = 17,785.55/x
3. Step 3: Cross multiply
   42,728.29x = 64,115.42 × 17,785.55
4. Step 4: Simplify right side
   42,728.29x = 1,140,328,079.54
5. Step 5: Solve for x
   x = 1,140,328,079.54/42,728.29
6. Step 6: Final answer
   x = 26,687.90