Finding the Third Proportional to 287.30 and 429.05

Step by Step Solution

1. Step 1: Write the proportion equation
   287.30 : 429.05 = 429.05 : x
2. Step 2: Convert to fraction form
   287.30/429.05 = 429.05/x
3. Step 3: Cross multiply
   287.30x = 429.05 × 429.05
4. Step 4: Simplify right side
   287.30x = 184,081.22
5. Step 5: Solve for x
   x = 184,081.22/287.30
6. Step 6: Final answer
   x = 640.74