Finding the Fourth Proportional to 436.42, 654.72 and 139.86

Step by Step Solution

1. Step 1: Write the proportion equation
   436.42 : 654.72 = 139.86 : x
2. Step 2: Convert to fraction form
   436.42/654.72 = 139.86/x
3. Step 3: Cross multiply
   436.42x = 654.72 × 139.86
4. Step 4: Simplify right side
   436.42x = 91,569.14
5. Step 5: Solve for x
   x = 91,569.14/436.42
6. Step 6: Final answer
   x = 209.82