Finding the Fourth Proportional to 78.16, 117.16 and 42.05

Step by Step Solution

1. Step 1: Write the proportion equation
   78.16 : 117.16 = 42.05 : x
2. Step 2: Convert to fraction form
   78.16/117.16 = 42.05/x
3. Step 3: Cross multiply
   78.16x = 117.16 × 42.05
4. Step 4: Simplify right side
   78.16x = 4,926.58
5. Step 5: Solve for x
   x = 4,926.58/78.16
6. Step 6: Final answer
   x = 63.03