Finding the Fourth Proportional to 86.90, 119.56 and 86.50

Step by Step Solution

1. Step 1: Write the proportion equation
   86.90 : 119.56 = 86.50 : x
2. Step 2: Convert to fraction form
   86.90/119.56 = 86.50/x
3. Step 3: Cross multiply
   86.90x = 119.56 × 86.50
4. Step 4: Simplify right side
   86.90x = 10,340.91
5. Step 5: Solve for x
   x = 10,340.91/86.90
6. Step 6: Final answer
   x = 119.00