Finding the Fourth Proportional to 78.68, 118.20 and 42.59

Step by Step Solution

1. Step 1: Write the proportion equation
   78.68 : 118.20 = 42.59 : x
2. Step 2: Convert to fraction form
   78.68/118.20 = 42.59/x
3. Step 3: Cross multiply
   78.68x = 118.20 × 42.59
4. Step 4: Simplify right side
   78.68x = 5,034.14
5. Step 5: Solve for x
   x = 5,034.14/78.68
6. Step 6: Final answer
   x = 63.98