Finding the Third Proportional to 1,200 and 1,309.50

Step by Step Solution

1. Step 1: Write the proportion equation
   1,200 : 1,309.50 = 1,309.50 : x
2. Step 2: Convert to fraction form
   1,200/1,309.50 = 1,309.50/x
3. Step 3: Cross multiply
   1,200x = 1,309.50 × 1,309.50
4. Step 4: Simplify right side
   1,200x = 1,714,790.25
5. Step 5: Solve for x
   x = 1,714,790.25/1,200
6. Step 6: Final answer
   x = 1,428.99