Finding the Fourth Proportional to 86.04, 128.37 and 78.30

Step by Step Solution

1. Step 1: Write the proportion equation
   86.04 : 128.37 = 78.30 : x
2. Step 2: Convert to fraction form
   86.04/128.37 = 78.30/x
3. Step 3: Cross multiply
   86.04x = 128.37 × 78.30
4. Step 4: Simplify right side
   86.04x = 10,051.37
5. Step 5: Solve for x
   x = 10,051.37/86.04
6. Step 6: Final answer
   x = 116.82