Finding the Fourth Proportional to 42,719.06, 64,084.74 and 13,139.40

Step by Step Solution

1. Step 1: Write the proportion equation
   42,719.06 : 64,084.74 = 13,139.40 : x
2. Step 2: Convert to fraction form
   42,719.06/64,084.74 = 13,139.40/x
3. Step 3: Cross multiply
   42,719.06x = 64,084.74 × 13,139.40
4. Step 4: Simplify right side
   42,719.06x = 842,035,032.76
5. Step 5: Solve for x
   x = 842,035,032.76/42,719.06
6. Step 6: Final answer
   x = 19,710.99