Finding the Fourth Proportional to 90.86, 136.36 and 42.78

Step by Step Solution

1. Step 1: Write the proportion equation
   90.86 : 136.36 = 42.78 : x
2. Step 2: Convert to fraction form
   90.86/136.36 = 42.78/x
3. Step 3: Cross multiply
   90.86x = 136.36 × 42.78
4. Step 4: Simplify right side
   90.86x = 5,833.48
5. Step 5: Solve for x
   x = 5,833.48/90.86
6. Step 6: Final answer
   x = 64.20