Finding the Fourth Proportional to 90.96, 136.38 and 42.21

Step by Step Solution

1. Step 1: Write the proportion equation
   90.96 : 136.38 = 42.21 : x
2. Step 2: Convert to fraction form
   90.96/136.38 = 42.21/x
3. Step 3: Cross multiply
   90.96x = 136.38 × 42.21
4. Step 4: Simplify right side
   90.96x = 5,755.92
5. Step 5: Solve for x
   x = 5,755.92/90.96
6. Step 6: Final answer
   x = 63.28