Finding the Fourth Proportional to 1,321.59, 1,978.71 and 669.12

Step by Step Solution

1. Step 1: Write the proportion equation
   1,321.59 : 1,978.71 = 669.12 : x
2. Step 2: Convert to fraction form
   1,321.59/1,978.71 = 669.12/x
3. Step 3: Cross multiply
   1,321.59x = 1,978.71 × 669.12
4. Step 4: Simplify right side
   1,321.59x = 1,323,994.44
5. Step 5: Solve for x
   x = 1,323,994.44/1,321.59
6. Step 6: Final answer
   x = 1,001.82