Finding the Fourth Proportional to 1,390.50, 2,083.43 and 978.77

Step by Step Solution

1. Step 1: Write the proportion equation
   1,390.50 : 2,083.43 = 978.77 : x
2. Step 2: Convert to fraction form
   1,390.50/2,083.43 = 978.77/x
3. Step 3: Cross multiply
   1,390.50x = 2,083.43 × 978.77
4. Step 4: Simplify right side
   1,390.50x = 2,039,198.78
5. Step 5: Solve for x
   x = 2,039,198.78/1,390.50
6. Step 6: Final answer
   x = 1,466.53