Finding the Fourth Proportional to 136.82, 188.72 and 90.12

Step by Step Solution

1. Step 1: Write the proportion equation
   136.82 : 188.72 = 90.12 : x
2. Step 2: Convert to fraction form
   136.82/188.72 = 90.12/x
3. Step 3: Cross multiply
   136.82x = 188.72 × 90.12
4. Step 4: Simplify right side
   136.82x = 17,007.00
5. Step 5: Solve for x
   x = 17,007.00/136.82
6. Step 6: Final answer
   x = 124.31