Finding the Fourth Proportional to 78.71, 118.17 and 71.19

Step by Step Solution

1. Step 1: Write the proportion equation
   78.71 : 118.17 = 71.19 : x
2. Step 2: Convert to fraction form
   78.71/118.17 = 71.19/x
3. Step 3: Cross multiply
   78.71x = 118.17 × 71.19
4. Step 4: Simplify right side
   78.71x = 8,412.52
5. Step 5: Solve for x
   x = 8,412.52/78.71
6. Step 6: Final answer
   x = 106.89