Finding the Fourth Proportional to 680.42, 1,019.83 and 290.31

Step by Step Solution

1. Step 1: Write the proportion equation
   680.42 : 1,019.83 = 290.31 : x
2. Step 2: Convert to fraction form
   680.42/1,019.83 = 290.31/x
3. Step 3: Cross multiply
   680.42x = 1,019.83 × 290.31
4. Step 4: Simplify right side
   680.42x = 296,066.85
5. Step 5: Solve for x
   x = 296,066.85/680.42
6. Step 6: Final answer
   x = 435.12