Finding the Third Proportional to 517.69 and 784.78

Step by Step Solution

1. Step 1: Write the proportion equation
   517.69 : 784.78 = 784.78 : x
2. Step 2: Convert to fraction form
   517.69/784.78 = 784.78/x
3. Step 3: Cross multiply
   517.69x = 784.78 × 784.78
4. Step 4: Simplify right side
   517.69x = 615,881.61
5. Step 5: Solve for x
   x = 615,881.61/517.69
6. Step 6: Final answer
   x = 1,189.68