Finding the Third Proportional to 200,280 and 428,990

Step by Step Solution

1. Step 1: Write the proportion equation
   200,280 : 428,990 = 428,990 : x
2. Step 2: Convert to fraction form
   200,280/428,990 = 428,990/x
3. Step 3: Cross multiply
   200,280x = 428,990 × 428,990
4. Step 4: Simplify right side
   200,280x = 184,032,420,100
5. Step 5: Solve for x
   x = 184,032,420,100/200,280
6. Step 6: Final answer
   x = 918,875.67