Finding the Fourth Proportional to 30,890.40, 42,606.72 and 21,801.12

Step by Step Solution

1. Step 1: Write the proportion equation
   30,890.40 : 42,606.72 = 21,801.12 : x
2. Step 2: Convert to fraction form
   30,890.40/42,606.72 = 21,801.12/x
3. Step 3: Cross multiply
   30,890.40x = 42,606.72 × 21,801.12
4. Step 4: Simplify right side
   30,890.40x = 928,874,215.53
5. Step 5: Solve for x
   x = 928,874,215.53/30,890.40
6. Step 6: Final answer
   x = 30,070.00