Finding the Third Proportional to 909 and 1,315.50

Step by Step Solution

1. Step 1: Write the proportion equation
   909 : 1,315.50 = 1,315.50 : x
2. Step 2: Convert to fraction form
   909/1,315.50 = 1,315.50/x
3. Step 3: Cross multiply
   909x = 1,315.50 × 1,315.50
4. Step 4: Simplify right side
   909x = 1,730,540.25
5. Step 5: Solve for x
   x = 1,730,540.25/909
6. Step 6: Final answer
   x = 1,903.78