Finding the Fourth Proportional to 78.42, 107.54 and 71.10

Step by Step Solution

1. Step 1: Write the proportion equation
   78.42 : 107.54 = 71.10 : x
2. Step 2: Convert to fraction form
   78.42/107.54 = 71.10/x
3. Step 3: Cross multiply
   78.42x = 107.54 × 71.10
4. Step 4: Simplify right side
   78.42x = 7,645.74
5. Step 5: Solve for x
   x = 7,645.74/78.42
6. Step 6: Final answer
   x = 97.50