Finding the Fourth Proportional to 2,216.65, 3,320.72 and 1,239.79

Step by Step Solution

1. Step 1: Write the proportion equation
   2,216.65 : 3,320.72 = 1,239.79 : x
2. Step 2: Convert to fraction form
   2,216.65/3,320.72 = 1,239.79/x
3. Step 3: Cross multiply
   2,216.65x = 3,320.72 × 1,239.79
4. Step 4: Simplify right side
   2,216.65x = 4,116,995.45
5. Step 5: Solve for x
   x = 4,116,995.45/2,216.65
6. Step 6: Final answer
   x = 1,857.31