Finding the Fourth Proportional to 86.78, 118.98 and 86.69

Step by Step Solution

1. Step 1: Write the proportion equation
   86.78 : 118.98 = 86.69 : x
2. Step 2: Convert to fraction form
   86.78/118.98 = 86.69/x
3. Step 3: Cross multiply
   86.78x = 118.98 × 86.69
4. Step 4: Simplify right side
   86.78x = 10,314.38
5. Step 5: Solve for x
   x = 10,314.38/86.78
6. Step 6: Final answer
   x = 118.86