Finding the Fourth Proportional to 21,870.63, 30,185.73 and 12,917.70

Step by Step Solution

1. Step 1: Write the proportion equation
   21,870.63 : 30,185.73 = 12,917.70 : x
2. Step 2: Convert to fraction form
   21,870.63/30,185.73 = 12,917.70/x
3. Step 3: Cross multiply
   21,870.63x = 30,185.73 × 12,917.70
4. Step 4: Simplify right side
   21,870.63x = 389,930,204.42
5. Step 5: Solve for x
   x = 389,930,204.42/21,870.63
6. Step 6: Final answer
   x = 17,828.94