Finding the Fourth Proportional to 78.87, 118.37 and 42.87

Step by Step Solution

1. Step 1: Write the proportion equation
   78.87 : 118.37 = 42.87 : x
2. Step 2: Convert to fraction form
   78.87/118.37 = 42.87/x
3. Step 3: Cross multiply
   78.87x = 118.37 × 42.87
4. Step 4: Simplify right side
   78.87x = 5,074.31
5. Step 5: Solve for x
   x = 5,074.31/78.87
6. Step 6: Final answer
   x = 64.34