Finding the Fourth Proportional to 1,658.95, 2,485.18 and 780.31

Step by Step Solution

1. Step 1: Write the proportion equation
   1,658.95 : 2,485.18 = 780.31 : x
2. Step 2: Convert to fraction form
   1,658.95/2,485.18 = 780.31/x
3. Step 3: Cross multiply
   1,658.95x = 2,485.18 × 780.31
4. Step 4: Simplify right side
   1,658.95x = 1,939,210.81
5. Step 5: Solve for x
   x = 1,939,210.81/1,658.95
6. Step 6: Final answer
   x = 1,168.94