Finding the Fourth Proportional to 72.78, 109.20 and 42.36

Step by Step Solution

1. Step 1: Write the proportion equation
   72.78 : 109.20 = 42.36 : x
2. Step 2: Convert to fraction form
   72.78/109.20 = 42.36/x
3. Step 3: Cross multiply
   72.78x = 109.20 × 42.36
4. Step 4: Simplify right side
   72.78x = 4,625.71
5. Step 5: Solve for x
   x = 4,625.71/72.78
6. Step 6: Final answer
   x = 63.56