Finding the Fourth Proportional to 111.42, 166.86 and 86.99

Step by Step Solution

1. Step 1: Write the proportion equation
   111.42 : 166.86 = 86.99 : x
2. Step 2: Convert to fraction form
   111.42/166.86 = 86.99/x
3. Step 3: Cross multiply
   111.42x = 166.86 × 86.99
4. Step 4: Simplify right side
   111.42x = 14,514.32
5. Step 5: Solve for x
   x = 14,514.32/111.42
6. Step 6: Final answer
   x = 130.27