Finding the Fourth Proportional to 1,986.96, 2,978.36 and 669.72

Step by Step Solution

1. Step 1: Write the proportion equation
   1,986.96 : 2,978.36 = 669.72 : x
2. Step 2: Convert to fraction form
   1,986.96/2,978.36 = 669.72/x
3. Step 3: Cross multiply
   1,986.96x = 2,978.36 × 669.72
4. Step 4: Simplify right side
   1,986.96x = 1,994,667.26
5. Step 5: Solve for x
   x = 1,994,667.26/1,986.96
6. Step 6: Final answer
   x = 1,003.88