Finding the Fourth Proportional to 78.80, 118.34 and 42.76

Step by Step Solution

1. Step 1: Write the proportion equation
   78.80 : 118.34 = 42.76 : x
2. Step 2: Convert to fraction form
   78.80/118.34 = 42.76/x
3. Step 3: Cross multiply
   78.80x = 118.34 × 42.76
4. Step 4: Simplify right side
   78.80x = 5,059.87
5. Step 5: Solve for x
   x = 5,059.87/78.80
6. Step 6: Final answer
   x = 64.21