Finding the Fourth Proportional to 39,870.84, 55,021.78 and 21,965.84

Step by Step Solution

1. Step 1: Write the proportion equation
   39,870.84 : 55,021.78 = 21,965.84 : x
2. Step 2: Convert to fraction form
   39,870.84/55,021.78 = 21,965.84/x
3. Step 3: Cross multiply
   39,870.84x = 55,021.78 × 21,965.84
4. Step 4: Simplify right side
   39,870.84x = 1,208,599,616.00
5. Step 5: Solve for x
   x = 1,208,599,616.00/39,870.84
6. Step 6: Final answer
   x = 30,312.87