Finding the Fourth Proportional to 1,388.86, 2,081.34 and 920.88

Step by Step Solution

1. Step 1: Write the proportion equation
   1,388.86 : 2,081.34 = 920.88 : x
2. Step 2: Convert to fraction form
   1,388.86/2,081.34 = 920.88/x
3. Step 3: Cross multiply
   1,388.86x = 2,081.34 × 920.88
4. Step 4: Simplify right side
   1,388.86x = 1,916,664.38
5. Step 5: Solve for x
   x = 1,916,664.38/1,388.86
6. Step 6: Final answer
   x = 1,380.03