Finding the Fourth Proportional to 1,287.83, 1,930.12 and 978.75

Step by Step Solution

1. Step 1: Write the proportion equation
   1,287.83 : 1,930.12 = 978.75 : x
2. Step 2: Convert to fraction form
   1,287.83/1,930.12 = 978.75/x
3. Step 3: Cross multiply
   1,287.83x = 1,930.12 × 978.75
4. Step 4: Simplify right side
   1,287.83x = 1,889,104.95
5. Step 5: Solve for x
   x = 1,889,104.95/1,287.83
6. Step 6: Final answer
   x = 1,466.89