Finding the Fourth Proportional to 111.67, 168.16 and 90.16

Step by Step Solution

1. Step 1: Write the proportion equation
   111.67 : 168.16 = 90.16 : x
2. Step 2: Convert to fraction form
   111.67/168.16 = 90.16/x
3. Step 3: Cross multiply
   111.67x = 168.16 × 90.16
4. Step 4: Simplify right side
   111.67x = 15,161.31
5. Step 5: Solve for x
   x = 15,161.31/111.67
6. Step 6: Final answer
   x = 135.77