Finding the Fourth Proportional to 71.50, 107.28 and 28.78

Step by Step Solution

1. Step 1: Write the proportion equation
   71.50 : 107.28 = 28.78 : x
2. Step 2: Convert to fraction form
   71.50/107.28 = 28.78/x
3. Step 3: Cross multiply
   71.50x = 107.28 × 28.78
4. Step 4: Simplify right side
   71.50x = 3,087.52
5. Step 5: Solve for x
   x = 3,087.52/71.50
6. Step 6: Final answer
   x = 43.18