Finding the Fourth Proportional to 78.68, 117.93 and 42.09

Step by Step Solution

1. Step 1: Write the proportion equation
   78.68 : 117.93 = 42.09 : x
2. Step 2: Convert to fraction form
   78.68/117.93 = 42.09/x
3. Step 3: Cross multiply
   78.68x = 117.93 × 42.09
4. Step 4: Simplify right side
   78.68x = 4,964.27
5. Step 5: Solve for x
   x = 4,964.27/78.68
6. Step 6: Final answer
   x = 63.10