Finding the Fourth Proportional to 78.42, 117.54 and 47.91

Step by Step Solution

1. Step 1: Write the proportion equation
   78.42 : 117.54 = 47.91 : x
2. Step 2: Convert to fraction form
   78.42/117.54 = 47.91/x
3. Step 3: Cross multiply
   78.42x = 117.54 × 47.91
4. Step 4: Simplify right side
   78.42x = 5,631.34
5. Step 5: Solve for x
   x = 5,631.34/78.42
6. Step 6: Final answer
   x = 71.81