Finding the Fourth Proportional to 31,082.24, 42,879.80 and 21,007

Step by Step Solution

1. Step 1: Write the proportion equation
   31,082.24 : 42,879.80 = 21,007 : x
2. Step 2: Convert to fraction form
   31,082.24/42,879.80 = 21,007/x
3. Step 3: Cross multiply
   31,082.24x = 42,879.80 × 21,007
4. Step 4: Simplify right side
   31,082.24x = 900,775,958.60
5. Step 5: Solve for x
   x = 900,775,958.60/31,082.24
6. Step 6: Final answer
   x = 28,980.41