Finding the Fourth Proportional to 109.76, 151.50 and 78.69

Step by Step Solution

1. Step 1: Write the proportion equation
   109.76 : 151.50 = 78.69 : x
2. Step 2: Convert to fraction form
   109.76/151.50 = 78.69/x
3. Step 3: Cross multiply
   109.76x = 151.50 × 78.69
4. Step 4: Simplify right side
   109.76x = 11,921.54
5. Step 5: Solve for x
   x = 11,921.54/109.76
6. Step 6: Final answer
   x = 108.62