Finding the Fourth Proportional to 1,119.72, 1,679.69 and 339.72

Step by Step Solution

1. Step 1: Write the proportion equation
   1,119.72 : 1,679.69 = 339.72 : x
2. Step 2: Convert to fraction form
   1,119.72/1,679.69 = 339.72/x
3. Step 3: Cross multiply
   1,119.72x = 1,679.69 × 339.72
4. Step 4: Simplify right side
   1,119.72x = 570,621.65
5. Step 5: Solve for x
   x = 570,621.65/1,119.72
6. Step 6: Final answer
   x = 509.61