Finding the Fourth Proportional to 1,108.72, 1,661.28 and 620.20

Step by Step Solution

1. Step 1: Write the proportion equation
   1,108.72 : 1,661.28 = 620.20 : x
2. Step 2: Convert to fraction form
   1,108.72/1,661.28 = 620.20/x
3. Step 3: Cross multiply
   1,108.72x = 1,661.28 × 620.20
4. Step 4: Simplify right side
   1,108.72x = 1,030,325.86
5. Step 5: Solve for x
   x = 1,030,325.86/1,108.72
6. Step 6: Final answer
   x = 929.29