Finding the Fourth Proportional to 2,007.78, 3,012.12 and 621.18

Step by Step Solution

1. Step 1: Write the proportion equation
   2,007.78 : 3,012.12 = 621.18 : x
2. Step 2: Convert to fraction form
   2,007.78/3,012.12 = 621.18/x
3. Step 3: Cross multiply
   2,007.78x = 3,012.12 × 621.18
4. Step 4: Simplify right side
   2,007.78x = 1,871,068.70
5. Step 5: Solve for x
   x = 1,871,068.70/2,007.78
6. Step 6: Final answer
   x = 931.91