Finding the Fourth Proportional to 78.56, 117.81 and 42.47

Step by Step Solution

1. Step 1: Write the proportion equation
   78.56 : 117.81 = 42.47 : x
2. Step 2: Convert to fraction form
   78.56/117.81 = 42.47/x
3. Step 3: Cross multiply
   78.56x = 117.81 × 42.47
4. Step 4: Simplify right side
   78.56x = 5,003.39
5. Step 5: Solve for x
   x = 5,003.39/78.56
6. Step 6: Final answer
   x = 63.69