Finding the Fourth Proportional to 78.77, 118.15 and 42.77

Step by Step Solution

1. Step 1: Write the proportion equation
   78.77 : 118.15 = 42.77 : x
2. Step 2: Convert to fraction form
   78.77/118.15 = 42.77/x
3. Step 3: Cross multiply
   78.77x = 118.15 × 42.77
4. Step 4: Simplify right side
   78.77x = 5,053.28
5. Step 5: Solve for x
   x = 5,053.28/78.77
6. Step 6: Final answer
   x = 64.15