Finding the Third Proportional to 919.69 and 1,399.78

Step by Step Solution

1. Step 1: Write the proportion equation
   919.69 : 1,399.78 = 1,399.78 : x
2. Step 2: Convert to fraction form
   919.69/1,399.78 = 1,399.78/x
3. Step 3: Cross multiply
   919.69x = 1,399.78 × 1,399.78
4. Step 4: Simplify right side
   919.69x = 1,959,387.55
5. Step 5: Solve for x
   x = 1,959,387.55/919.69
6. Step 6: Final answer
   x = 2,130.49