Finding the Fourth Proportional to 42,640.80, 63,955.60 and 13,061.60

Step by Step Solution

1. Step 1: Write the proportion equation
   42,640.80 : 63,955.60 = 13,061.60 : x
2. Step 2: Convert to fraction form
   42,640.80/63,955.60 = 13,061.60/x
3. Step 3: Cross multiply
   42,640.80x = 63,955.60 × 13,061.60
4. Step 4: Simplify right side
   42,640.80x = 835,362,464.96
5. Step 5: Solve for x
   x = 835,362,464.96/42,640.80
6. Step 6: Final answer
   x = 19,590.68