Finding the Third Proportional to 987 and 1,389.50

Step by Step Solution

1. Step 1: Write the proportion equation
   987 : 1,389.50 = 1,389.50 : x
2. Step 2: Convert to fraction form
   987/1,389.50 = 1,389.50/x
3. Step 3: Cross multiply
   987x = 1,389.50 × 1,389.50
4. Step 4: Simplify right side
   987x = 1,930,710.25
5. Step 5: Solve for x
   x = 1,930,710.25/987
6. Step 6: Final answer
   x = 1,956.14