Finding the Fourth Proportional to 39,870.81, 55,020.42 and 21,965.76

Step by Step Solution

1. Step 1: Write the proportion equation
   39,870.81 : 55,020.42 = 21,965.76 : x
2. Step 2: Convert to fraction form
   39,870.81/55,020.42 = 21,965.76/x
3. Step 3: Cross multiply
   39,870.81x = 55,020.42 × 21,965.76
4. Step 4: Simplify right side
   39,870.81x = 1,208,565,340.82
5. Step 5: Solve for x
   x = 1,208,565,340.82/39,870.81
6. Step 6: Final answer
   x = 30,312.03