Finding the Fourth Proportional to 21,012.16, 31,499.16 and 10,485.40

Step by Step Solution

1. Step 1: Write the proportion equation
   21,012.16 : 31,499.16 = 10,485.40 : x
2. Step 2: Convert to fraction form
   21,012.16/31,499.16 = 10,485.40/x
3. Step 3: Cross multiply
   21,012.16x = 31,499.16 × 10,485.40
4. Step 4: Simplify right side
   21,012.16x = 330,281,292.26
5. Step 5: Solve for x
   x = 330,281,292.26/21,012.16
6. Step 6: Final answer
   x = 15,718.58