Finding the Fourth Proportional to 1,019.61, 1,406.59 and 665.55

Step by Step Solution

1. Step 1: Write the proportion equation
   1,019.61 : 1,406.59 = 665.55 : x
2. Step 2: Convert to fraction form
   1,019.61/1,406.59 = 665.55/x
3. Step 3: Cross multiply
   1,019.61x = 1,406.59 × 665.55
4. Step 4: Simplify right side
   1,019.61x = 936,154.31
5. Step 5: Solve for x
   x = 936,154.31/1,019.61
6. Step 6: Final answer
   x = 918.15