Finding the Third Proportional to 1,255.78 and 1,989.98

Step by Step Solution

1. Step 1: Write the proportion equation
   1,255.78 : 1,989.98 = 1,989.98 : x
2. Step 2: Convert to fraction form
   1,255.78/1,989.98 = 1,989.98/x
3. Step 3: Cross multiply
   1,255.78x = 1,989.98 × 1,989.98
4. Step 4: Simplify right side
   1,255.78x = 3,960,037.81
5. Step 5: Solve for x
   x = 3,960,037.81/1,255.78
6. Step 6: Final answer
   x = 3,153.45