Finding the Fourth Proportional to 42,715.72, 64,087.28 and 20,530.70

Step by Step Solution

1. Step 1: Write the proportion equation
   42,715.72 : 64,087.28 = 20,530.70 : x
2. Step 2: Convert to fraction form
   42,715.72/64,087.28 = 20,530.70/x
3. Step 3: Cross multiply
   42,715.72x = 64,087.28 × 20,530.70
4. Step 4: Simplify right side
   42,715.72x = 1,315,756,719.50
5. Step 5: Solve for x
   x = 1,315,756,719.50/42,715.72
6. Step 6: Final answer
   x = 30,802.63