Finding the Fourth Proportional to 158.56, 218.72 and 139.20

Step by Step Solution

1. Step 1: Write the proportion equation
   158.56 : 218.72 = 139.20 : x
2. Step 2: Convert to fraction form
   158.56/218.72 = 139.20/x
3. Step 3: Cross multiply
   158.56x = 218.72 × 139.20
4. Step 4: Simplify right side
   158.56x = 30,445.82
5. Step 5: Solve for x
   x = 30,445.82/158.56
6. Step 6: Final answer
   x = 192.01