Finding the Fourth Proportional to 109.28, 164.03 and 78.71

Step by Step Solution

1. Step 1: Write the proportion equation
   109.28 : 164.03 = 78.71 : x
2. Step 2: Convert to fraction form
   109.28/164.03 = 78.71/x
3. Step 3: Cross multiply
   109.28x = 164.03 × 78.71
4. Step 4: Simplify right side
   109.28x = 12,909.59
5. Step 5: Solve for x
   x = 12,909.59/109.28
6. Step 6: Final answer
   x = 118.13