Finding the Fourth Proportional to 21,020.24, 31,531.02 and 7,870.10

Step by Step Solution

1. Step 1: Write the proportion equation
   21,020.24 : 31,531.02 = 7,870.10 : x
2. Step 2: Convert to fraction form
   21,020.24/31,531.02 = 7,870.10/x
3. Step 3: Cross multiply
   21,020.24x = 31,531.02 × 7,870.10
4. Step 4: Simplify right side
   21,020.24x = 248,152,280.50
5. Step 5: Solve for x
   x = 248,152,280.50/21,020.24
6. Step 6: Final answer
   x = 11,805.40