Finding the Fourth Proportional to 1,379.69, 2,066.55 and 648.17

Step by Step Solution

1. Step 1: Write the proportion equation
   1,379.69 : 2,066.55 = 648.17 : x
2. Step 2: Convert to fraction form
   1,379.69/2,066.55 = 648.17/x
3. Step 3: Cross multiply
   1,379.69x = 2,066.55 × 648.17
4. Step 4: Simplify right side
   1,379.69x = 1,339,465.38
5. Step 5: Solve for x
   x = 1,339,465.38/1,379.69
6. Step 6: Final answer
   x = 970.85