Finding the Fourth Proportional to 90.80, 136.16 and 42.72

Step by Step Solution

1. Step 1: Write the proportion equation
   90.80 : 136.16 = 42.72 : x
2. Step 2: Convert to fraction form
   90.80/136.16 = 42.72/x
3. Step 3: Cross multiply
   90.80x = 136.16 × 42.72
4. Step 4: Simplify right side
   90.80x = 5,816.76
5. Step 5: Solve for x
   x = 5,816.76/90.80
6. Step 6: Final answer
   x = 64.06