Finding the Fourth Proportional to 1,418.80, 2,128.56 and 978.96

Step by Step Solution

1. Step 1: Write the proportion equation
   1,418.80 : 2,128.56 = 978.96 : x
2. Step 2: Convert to fraction form
   1,418.80/2,128.56 = 978.96/x
3. Step 3: Cross multiply
   1,418.80x = 2,128.56 × 978.96
4. Step 4: Simplify right side
   1,418.80x = 2,083,775.10
5. Step 5: Solve for x
   x = 2,083,775.10/1,418.80
6. Step 6: Final answer
   x = 1,468.69