Finding the Fourth Proportional to 1,011.89, 1,518.05 and 318.76

Step by Step Solution

1. Step 1: Write the proportion equation
   1,011.89 : 1,518.05 = 318.76 : x
2. Step 2: Convert to fraction form
   1,011.89/1,518.05 = 318.76/x
3. Step 3: Cross multiply
   1,011.89x = 1,518.05 × 318.76
4. Step 4: Simplify right side
   1,011.89x = 483,890.62
5. Step 5: Solve for x
   x = 483,890.62/1,011.89
6. Step 6: Final answer
   x = 478.20