Finding the Fourth Proportional to 42,721.77, 64,088.79 and 13,142.10

Step by Step Solution

1. Step 1: Write the proportion equation
   42,721.77 : 64,088.79 = 13,142.10 : x
2. Step 2: Convert to fraction form
   42,721.77/64,088.79 = 13,142.10/x
3. Step 3: Cross multiply
   42,721.77x = 64,088.79 × 13,142.10
4. Step 4: Simplify right side
   42,721.77x = 842,261,287.06
5. Step 5: Solve for x
   x = 842,261,287.06/42,721.77
6. Step 6: Final answer
   x = 19,715.04