Finding the Third Proportional to 139.78 and 288.56

Step by Step Solution

1. Step 1: Write the proportion equation
   139.78 : 288.56 = 288.56 : x
2. Step 2: Convert to fraction form
   139.78/288.56 = 288.56/x
3. Step 3: Cross multiply
   139.78x = 288.56 × 288.56
4. Step 4: Simplify right side
   139.78x = 83,268.32
5. Step 5: Solve for x
   x = 83,268.32/139.78
6. Step 6: Final answer
   x = 595.70