Finding the Fourth Proportional to 42,719.27, 64,085.04 and 13,139.60

Step by Step Solution

1. Step 1: Write the proportion equation
   42,719.27 : 64,085.04 = 13,139.60 : x
2. Step 2: Convert to fraction form
   42,719.27/64,085.04 = 13,139.60/x
3. Step 3: Cross multiply
   42,719.27x = 64,085.04 × 13,139.60
4. Step 4: Simplify right side
   42,719.27x = 842,051,471.16
5. Step 5: Solve for x
   x = 842,051,471.16/42,719.27
6. Step 6: Final answer
   x = 19,711.28