Finding the Fourth Proportional to 78.81, 118.13 and 42.77

Step by Step Solution

1. Step 1: Write the proportion equation
   78.81 : 118.13 = 42.77 : x
2. Step 2: Convert to fraction form
   78.81/118.13 = 42.77/x
3. Step 3: Cross multiply
   78.81x = 118.13 × 42.77
4. Step 4: Simplify right side
   78.81x = 5,051.62
5. Step 5: Solve for x
   x = 5,051.62/78.81
6. Step 6: Final answer
   x = 64.10