Finding the Fourth Proportional to 109.50, 150.92 and 100.78

Step by Step Solution

1. Step 1: Write the proportion equation
   109.50 : 150.92 = 100.78 : x
2. Step 2: Convert to fraction form
   109.50/150.92 = 100.78/x
3. Step 3: Cross multiply
   109.50x = 150.92 × 100.78
4. Step 4: Simplify right side
   109.50x = 15,209.72
5. Step 5: Solve for x
   x = 15,209.72/109.50
6. Step 6: Final answer
   x = 138.90