Finding the Fourth Proportional to 1,112.21, 1,667.79 and 418.34

Step by Step Solution

1. Step 1: Write the proportion equation
   1,112.21 : 1,667.79 = 418.34 : x
2. Step 2: Convert to fraction form
   1,112.21/1,667.79 = 418.34/x
3. Step 3: Cross multiply
   1,112.21x = 1,667.79 × 418.34
4. Step 4: Simplify right side
   1,112.21x = 697,703.27
5. Step 5: Solve for x
   x = 697,703.27/1,112.21
6. Step 6: Final answer
   x = 627.31