Finding the Fourth Proportional to 1,398.72, 1,932.74 and 1,005.06

Step by Step Solution

1. Step 1: Write the proportion equation
   1,398.72 : 1,932.74 = 1,005.06 : x
2. Step 2: Convert to fraction form
   1,398.72/1,932.74 = 1,005.06/x
3. Step 3: Cross multiply
   1,398.72x = 1,932.74 × 1,005.06
4. Step 4: Simplify right side
   1,398.72x = 1,942,519.66
5. Step 5: Solve for x
   x = 1,942,519.66/1,398.72
6. Step 6: Final answer
   x = 1,388.78