Finding the Fourth Proportional to 109.34, 150.71 and 78.20

Step by Step Solution

1. Step 1: Write the proportion equation
   109.34 : 150.71 = 78.20 : x
2. Step 2: Convert to fraction form
   109.34/150.71 = 78.20/x
3. Step 3: Cross multiply
   109.34x = 150.71 × 78.20
4. Step 4: Simplify right side
   109.34x = 11,785.52
5. Step 5: Solve for x
   x = 11,785.52/109.34
6. Step 6: Final answer
   x = 107.79