Finding the Fourth Proportional to 1,397.89, 1,929.06 and 874.21

Step by Step Solution

1. Step 1: Write the proportion equation
   1,397.89 : 1,929.06 = 874.21 : x
2. Step 2: Convert to fraction form
   1,397.89/1,929.06 = 874.21/x
3. Step 3: Cross multiply
   1,397.89x = 1,929.06 × 874.21
4. Step 4: Simplify right side
   1,397.89x = 1,686,403.54
5. Step 5: Solve for x
   x = 1,686,403.54/1,397.89
6. Step 6: Final answer
   x = 1,206.39