Finding the Fourth Proportional to 78.67, 117.99 and 42.58

Step by Step Solution

1. Step 1: Write the proportion equation
   78.67 : 117.99 = 42.58 : x
2. Step 2: Convert to fraction form
   78.67/117.99 = 42.58/x
3. Step 3: Cross multiply
   78.67x = 117.99 × 42.58
4. Step 4: Simplify right side
   78.67x = 5,024.01
5. Step 5: Solve for x
   x = 5,024.01/78.67
6. Step 6: Final answer
   x = 63.86