Finding the Fourth Proportional to 1,339.89, 2,009.76 and 415.42

Step by Step Solution

1. Step 1: Write the proportion equation
   1,339.89 : 2,009.76 = 415.42 : x
2. Step 2: Convert to fraction form
   1,339.89/2,009.76 = 415.42/x
3. Step 3: Cross multiply
   1,339.89x = 2,009.76 × 415.42
4. Step 4: Simplify right side
   1,339.89x = 834,894.50
5. Step 5: Solve for x
   x = 834,894.50/1,339.89
6. Step 6: Final answer
   x = 623.11