Finding the Fourth Proportional to 1,380.16, 1,904.68 and 820.96

Step by Step Solution

1. Step 1: Write the proportion equation
   1,380.16 : 1,904.68 = 820.96 : x
2. Step 2: Convert to fraction form
   1,380.16/1,904.68 = 820.96/x
3. Step 3: Cross multiply
   1,380.16x = 1,904.68 × 820.96
4. Step 4: Simplify right side
   1,380.16x = 1,563,666.09
5. Step 5: Solve for x
   x = 1,563,666.09/1,380.16
6. Step 6: Final answer
   x = 1,132.96