Finding the Fourth Proportional to 1,111.28, 1,667.20 and 417.98

Step by Step Solution

1. Step 1: Write the proportion equation
   1,111.28 : 1,667.20 = 417.98 : x
2. Step 2: Convert to fraction form
   1,111.28/1,667.20 = 417.98/x
3. Step 3: Cross multiply
   1,111.28x = 1,667.20 × 417.98
4. Step 4: Simplify right side
   1,111.28x = 696,856.26
5. Step 5: Solve for x
   x = 696,856.26/1,111.28
6. Step 6: Final answer
   x = 627.08