Finding the Fourth Proportional to 1,109.21, 1,662.65 and 415.43

Step by Step Solution

1. Step 1: Write the proportion equation
   1,109.21 : 1,662.65 = 415.43 : x
2. Step 2: Convert to fraction form
   1,109.21/1,662.65 = 415.43/x
3. Step 3: Cross multiply
   1,109.21x = 1,662.65 × 415.43
4. Step 4: Simplify right side
   1,109.21x = 690,704.30
5. Step 5: Solve for x
   x = 690,704.30/1,109.21
6. Step 6: Final answer
   x = 622.70