Finding the Fourth Proportional to 1,388.61, 2,081.40 and 1,042.64

Step by Step Solution

1. Step 1: Write the proportion equation
   1,388.61 : 2,081.40 = 1,042.64 : x
2. Step 2: Convert to fraction form
   1,388.61/2,081.40 = 1,042.64/x
3. Step 3: Cross multiply
   1,388.61x = 2,081.40 × 1,042.64
4. Step 4: Simplify right side
   1,388.61x = 2,170,144.38
5. Step 5: Solve for x
   x = 2,170,144.38/1,388.61
6. Step 6: Final answer
   x = 1,562.82