Finding the Third Proportional to 1,287.56 and 1,999.69

Step by Step Solution

1. Step 1: Write the proportion equation
   1,287.56 : 1,999.69 = 1,999.69 : x
2. Step 2: Convert to fraction form
   1,287.56/1,999.69 = 1,999.69/x
3. Step 3: Cross multiply
   1,287.56x = 1,999.69 × 1,999.69
4. Step 4: Simplify right side
   1,287.56x = 3,998,750.10
5. Step 5: Solve for x
   x = 3,998,750.10/1,287.56
6. Step 6: Final answer
   x = 3,105.67