Finding the Fourth Proportional to 1,321.76, 1,985.52 and 1,078.88

Step by Step Solution

1. Step 1: Write the proportion equation
   1,321.76 : 1,985.52 = 1,078.88 : x
2. Step 2: Convert to fraction form
   1,321.76/1,985.52 = 1,078.88/x
3. Step 3: Cross multiply
   1,321.76x = 1,985.52 × 1,078.88
4. Step 4: Simplify right side
   1,321.76x = 2,142,137.82
5. Step 5: Solve for x
   x = 2,142,137.82/1,321.76
6. Step 6: Final answer
   x = 1,620.67