Finding the Fourth Proportional to 78.15, 117.08 and 42.10

Step by Step Solution

1. Step 1: Write the proportion equation
   78.15 : 117.08 = 42.10 : x
2. Step 2: Convert to fraction form
   78.15/117.08 = 42.10/x
3. Step 3: Cross multiply
   78.15x = 117.08 × 42.10
4. Step 4: Simplify right side
   78.15x = 4,929.17
5. Step 5: Solve for x
   x = 4,929.17/78.15
6. Step 6: Final answer
   x = 63.08