Finding the Fourth Proportional to 30,740.72, 42,410.79 and 20,136.20

Step by Step Solution

1. Step 1: Write the proportion equation
   30,740.72 : 42,410.79 = 20,136.20 : x
2. Step 2: Convert to fraction form
   30,740.72/42,410.79 = 20,136.20/x
3. Step 3: Cross multiply
   30,740.72x = 42,410.79 × 20,136.20
4. Step 4: Simplify right side
   30,740.72x = 853,991,937.54
5. Step 5: Solve for x
   x = 853,991,937.54/30,740.72
6. Step 6: Final answer
   x = 27,780.48