Finding the Fourth Proportional to 1,216.69, 1,679.03 and 664.69

Step by Step Solution

1. Step 1: Write the proportion equation
   1,216.69 : 1,679.03 = 664.69 : x
2. Step 2: Convert to fraction form
   1,216.69/1,679.03 = 664.69/x
3. Step 3: Cross multiply
   1,216.69x = 1,679.03 × 664.69
4. Step 4: Simplify right side
   1,216.69x = 1,116,034.45
5. Step 5: Solve for x
   x = 1,116,034.45/1,216.69
6. Step 6: Final answer
   x = 917.27