Finding the Fourth Proportional to 86.54, 118.72 and 85.10

Step by Step Solution

1. Step 1: Write the proportion equation
   86.54 : 118.72 = 85.10 : x
2. Step 2: Convert to fraction form
   86.54/118.72 = 85.10/x
3. Step 3: Cross multiply
   86.54x = 118.72 × 85.10
4. Step 4: Simplify right side
   86.54x = 10,103.07
5. Step 5: Solve for x
   x = 10,103.07/86.54
6. Step 6: Final answer
   x = 116.74