Finding the Fourth Proportional to 72.78, 108.90 and 42.36

Step by Step Solution

1. Step 1: Write the proportion equation
   72.78 : 108.90 = 42.36 : x
2. Step 2: Convert to fraction form
   72.78/108.90 = 42.36/x
3. Step 3: Cross multiply
   72.78x = 108.90 × 42.36
4. Step 4: Simplify right side
   72.78x = 4,613.00
5. Step 5: Solve for x
   x = 4,613.00/72.78
6. Step 6: Final answer
   x = 63.38