Finding the Fourth Proportional to 78.22, 117.34 and 42.18

Step by Step Solution

1. Step 1: Write the proportion equation
   78.22 : 117.34 = 42.18 : x
2. Step 2: Convert to fraction form
   78.22/117.34 = 42.18/x
3. Step 3: Cross multiply
   78.22x = 117.34 × 42.18
4. Step 4: Simplify right side
   78.22x = 4,949.40
5. Step 5: Solve for x
   x = 4,949.40/78.22
6. Step 6: Final answer
   x = 63.28