Finding the Third Proportional to 1,407 and 2,128.50

Step by Step Solution

1. Step 1: Write the proportion equation
   1,407 : 2,128.50 = 2,128.50 : x
2. Step 2: Convert to fraction form
   1,407/2,128.50 = 2,128.50/x
3. Step 3: Cross multiply
   1,407x = 2,128.50 × 2,128.50
4. Step 4: Simplify right side
   1,407x = 4,530,512.25
5. Step 5: Solve for x
   x = 4,530,512.25/1,407
6. Step 6: Final answer
   x = 3,219.98