Finding the Fourth Proportional to 90.25, 135.42 and 42.15

Step by Step Solution

1. Step 1: Write the proportion equation
   90.25 : 135.42 = 42.15 : x
2. Step 2: Convert to fraction form
   90.25/135.42 = 42.15/x
3. Step 3: Cross multiply
   90.25x = 135.42 × 42.15
4. Step 4: Simplify right side
   90.25x = 5,707.28
5. Step 5: Solve for x
   x = 5,707.28/90.25
6. Step 6: Final answer
   x = 63.24