Finding the Third Proportional to 2,128.50 and 3,111.75

Step by Step Solution

1. Step 1: Write the proportion equation
   2,128.50 : 3,111.75 = 3,111.75 : x
2. Step 2: Convert to fraction form
   2,128.50/3,111.75 = 3,111.75/x
3. Step 3: Cross multiply
   2,128.50x = 3,111.75 × 3,111.75
4. Step 4: Simplify right side
   2,128.50x = 9,682,988.06
5. Step 5: Solve for x
   x = 9,682,988.06/2,128.50
6. Step 6: Final answer
   x = 4,549.21