Finding the Fourth Proportional to 78.69, 118.17 and 71.13

Step by Step Solution

1. Step 1: Write the proportion equation
   78.69 : 118.17 = 71.13 : x
2. Step 2: Convert to fraction form
   78.69/118.17 = 71.13/x
3. Step 3: Cross multiply
   78.69x = 118.17 × 71.13
4. Step 4: Simplify right side
   78.69x = 8,405.43
5. Step 5: Solve for x
   x = 8,405.43/78.69
6. Step 6: Final answer
   x = 106.82