Finding the Fourth Proportional to 820.29, 1,128.56 and 678.81

Step by Step Solution

1. Step 1: Write the proportion equation
   820.29 : 1,128.56 = 678.81 : x
2. Step 2: Convert to fraction form
   820.29/1,128.56 = 678.81/x
3. Step 3: Cross multiply
   820.29x = 1,128.56 × 678.81
4. Step 4: Simplify right side
   820.29x = 766,074.42
5. Step 5: Solve for x
   x = 766,074.42/820.29
6. Step 6: Final answer
   x = 933.91