Finding the Fourth Proportional to 1,398.30, 1,931.67 and 1,355.10

Step by Step Solution

1. Step 1: Write the proportion equation
   1,398.30 : 1,931.67 = 1,355.10 : x
2. Step 2: Convert to fraction form
   1,398.30/1,931.67 = 1,355.10/x
3. Step 3: Cross multiply
   1,398.30x = 1,931.67 × 1,355.10
4. Step 4: Simplify right side
   1,398.30x = 2,617,606.02
5. Step 5: Solve for x
   x = 2,617,606.02/1,398.30
6. Step 6: Final answer
   x = 1,871.99