Finding the Fourth Proportional to 1,685.78, 2,530.49 and 1,279.36

Step by Step Solution

1. Step 1: Write the proportion equation
   1,685.78 : 2,530.49 = 1,279.36 : x
2. Step 2: Convert to fraction form
   1,685.78/2,530.49 = 1,279.36/x
3. Step 3: Cross multiply
   1,685.78x = 2,530.49 × 1,279.36
4. Step 4: Simplify right side
   1,685.78x = 3,237,407.69
5. Step 5: Solve for x
   x = 3,237,407.69/1,685.78
6. Step 6: Final answer
   x = 1,920.42