Finding the Fourth Proportional to 1,007.39, 1,390.15 and 609.15

Step by Step Solution

1. Step 1: Write the proportion equation
   1,007.39 : 1,390.15 = 609.15 : x
2. Step 2: Convert to fraction form
   1,007.39/1,390.15 = 609.15/x
3. Step 3: Cross multiply
   1,007.39x = 1,390.15 × 609.15
4. Step 4: Simplify right side
   1,007.39x = 846,803.26
5. Step 5: Solve for x
   x = 846,803.26/1,007.39
6. Step 6: Final answer
   x = 840.59