Finding the Fourth Proportional to 1,216.19, 1,678.27 and 718.71

Step by Step Solution

1. Step 1: Write the proportion equation
   1,216.19 : 1,678.27 = 718.71 : x
2. Step 2: Convert to fraction form
   1,216.19/1,678.27 = 718.71/x
3. Step 3: Cross multiply
   1,216.19x = 1,678.27 × 718.71
4. Step 4: Simplify right side
   1,216.19x = 1,206,189.43
5. Step 5: Solve for x
   x = 1,206,189.43/1,216.19
6. Step 6: Final answer
   x = 991.78