Finding the Fourth Proportional to 1,549.91, 2,139.18 and 920.78

Step by Step Solution

1. Step 1: Write the proportion equation
   1,549.91 : 2,139.18 = 920.78 : x
2. Step 2: Convert to fraction form
   1,549.91/2,139.18 = 920.78/x
3. Step 3: Cross multiply
   1,549.91x = 2,139.18 × 920.78
4. Step 4: Simplify right side
   1,549.91x = 1,969,703.46
5. Step 5: Solve for x
   x = 1,969,703.46/1,549.91
6. Step 6: Final answer
   x = 1,270.85