Finding the Fourth Proportional to 90.24, 135.22 and 78.72

Step by Step Solution

1. Step 1: Write the proportion equation
   90.24 : 135.22 = 78.72 : x
2. Step 2: Convert to fraction form
   90.24/135.22 = 78.72/x
3. Step 3: Cross multiply
   90.24x = 135.22 × 78.72
4. Step 4: Simplify right side
   90.24x = 10,644.52
5. Step 5: Solve for x
   x = 10,644.52/90.24
6. Step 6: Final answer
   x = 117.96