Finding the Fourth Proportional to 1,345.90, 2,017.12 and 728.31

Step by Step Solution

1. Step 1: Write the proportion equation
   1,345.90 : 2,017.12 = 728.31 : x
2. Step 2: Convert to fraction form
   1,345.90/2,017.12 = 728.31/x
3. Step 3: Cross multiply
   1,345.90x = 2,017.12 × 728.31
4. Step 4: Simplify right side
   1,345.90x = 1,469,089.78
5. Step 5: Solve for x
   x = 1,469,089.78/1,345.90
6. Step 6: Final answer
   x = 1,091.53