Finding the Fourth Proportional to 90.15, 135.22 and 42.09

Step by Step Solution

1. Step 1: Write the proportion equation
   90.15 : 135.22 = 42.09 : x
2. Step 2: Convert to fraction form
   90.15/135.22 = 42.09/x
3. Step 3: Cross multiply
   90.15x = 135.22 × 42.09
4. Step 4: Simplify right side
   90.15x = 5,691.41
5. Step 5: Solve for x
   x = 5,691.41/90.15
6. Step 6: Final answer
   x = 63.13