Finding the Third Proportional to 1,138 and 1,298.50

Step by Step Solution

1. Step 1: Write the proportion equation
   1,138 : 1,298.50 = 1,298.50 : x
2. Step 2: Convert to fraction form
   1,138/1,298.50 = 1,298.50/x
3. Step 3: Cross multiply
   1,138x = 1,298.50 × 1,298.50
4. Step 4: Simplify right side
   1,138x = 1,686,102.25
5. Step 5: Solve for x
   x = 1,686,102.25/1,138
6. Step 6: Final answer
   x = 1,481.64