Finding the Fourth Proportional to 1,339.72, 2,009.76 and 415.34

Step by Step Solution

1. Step 1: Write the proportion equation
   1,339.72 : 2,009.76 = 415.34 : x
2. Step 2: Convert to fraction form
   1,339.72/2,009.76 = 415.34/x
3. Step 3: Cross multiply
   1,339.72x = 2,009.76 × 415.34
4. Step 4: Simplify right side
   1,339.72x = 834,733.72
5. Step 5: Solve for x
   x = 834,733.72/1,339.72
6. Step 6: Final answer
   x = 623.07