Finding the Fourth Proportional to 78.69, 116.39 and 78.69

Step by Step Solution

1. Step 1: Write the proportion equation
   78.69 : 116.39 = 78.69 : x
2. Step 2: Convert to fraction form
   78.69/116.39 = 78.69/x
3. Step 3: Cross multiply
   78.69x = 116.39 × 78.69
4. Step 4: Simplify right side
   78.69x = 9,159.36
5. Step 5: Solve for x
   x = 9,159.36/78.69
6. Step 6: Final answer
   x = 116.39