Finding the Fourth Proportional to 111.15, 165.96 and 90.81

Step by Step Solution

1. Step 1: Write the proportion equation
   111.15 : 165.96 = 90.81 : x
2. Step 2: Convert to fraction form
   111.15/165.96 = 90.81/x
3. Step 3: Cross multiply
   111.15x = 165.96 × 90.81
4. Step 4: Simplify right side
   111.15x = 15,070.83
5. Step 5: Solve for x
   x = 15,070.83/111.15
6. Step 6: Final answer
   x = 135.59