Finding the Fourth Proportional to 136.72, 188.72 and 109.28

Step by Step Solution

1. Step 1: Write the proportion equation
   136.72 : 188.72 = 109.28 : x
2. Step 2: Convert to fraction form
   136.72/188.72 = 109.28/x
3. Step 3: Cross multiply
   136.72x = 188.72 × 109.28
4. Step 4: Simplify right side
   136.72x = 20,623.32
5. Step 5: Solve for x
   x = 20,623.32/136.72
6. Step 6: Final answer
   x = 150.84