Finding the Fourth Proportional to 238.50, 357.91 and 86.50

Step by Step Solution

1. Step 1: Write the proportion equation
   238.50 : 357.91 = 86.50 : x
2. Step 2: Convert to fraction form
   238.50/357.91 = 86.50/x
3. Step 3: Cross multiply
   238.50x = 357.91 × 86.50
4. Step 4: Simplify right side
   238.50x = 30,959.22
5. Step 5: Solve for x
   x = 30,959.22/238.50
6. Step 6: Final answer
   x = 129.81