Finding the Fourth Proportional to 90.78, 136.22 and 42.70

Step by Step Solution

1. Step 1: Write the proportion equation
   90.78 : 136.22 = 42.70 : x
2. Step 2: Convert to fraction form
   90.78/136.22 = 42.70/x
3. Step 3: Cross multiply
   90.78x = 136.22 × 42.70
4. Step 4: Simplify right side
   90.78x = 5,816.59
5. Step 5: Solve for x
   x = 5,816.59/90.78
6. Step 6: Final answer
   x = 64.07