Finding the Fourth Proportional to 90.96, 136.40 and 42.88

Step by Step Solution

1. Step 1: Write the proportion equation
   90.96 : 136.40 = 42.88 : x
2. Step 2: Convert to fraction form
   90.96/136.40 = 42.88/x
3. Step 3: Cross multiply
   90.96x = 136.40 × 42.88
4. Step 4: Simplify right side
   90.96x = 5,848.83
5. Step 5: Solve for x
   x = 5,848.83/90.96
6. Step 6: Final answer
   x = 64.30