Finding the Fourth Proportional to 200.64, 300.69 and 139.89

Step by Step Solution

1. Step 1: Write the proportion equation
   200.64 : 300.69 = 139.89 : x
2. Step 2: Convert to fraction form
   200.64/300.69 = 139.89/x
3. Step 3: Cross multiply
   200.64x = 300.69 × 139.89
4. Step 4: Simplify right side
   200.64x = 42,063.52
5. Step 5: Solve for x
   x = 42,063.52/200.64
6. Step 6: Final answer
   x = 209.65