Finding the Fourth Proportional to 109.20, 150.78 and 91.50

Step by Step Solution

1. Step 1: Write the proportion equation
   109.20 : 150.78 = 91.50 : x
2. Step 2: Convert to fraction form
   109.20/150.78 = 91.50/x
3. Step 3: Cross multiply
   109.20x = 150.78 × 91.50
4. Step 4: Simplify right side
   109.20x = 13,796.37
5. Step 5: Solve for x
   x = 13,796.37/109.20
6. Step 6: Final answer
   x = 126.34