Finding the Third Proportional to 1,266.19 and 1,387.69

Step by Step Solution

1. Step 1: Write the proportion equation
   1,266.19 : 1,387.69 = 1,387.69 : x
2. Step 2: Convert to fraction form
   1,266.19/1,387.69 = 1,387.69/x
3. Step 3: Cross multiply
   1,266.19x = 1,387.69 × 1,387.69
4. Step 4: Simplify right side
   1,266.19x = 1,925,676.60
5. Step 5: Solve for x
   x = 1,925,676.60/1,266.19
6. Step 6: Final answer
   x = 1,520.85