Finding the Fourth Proportional to 21,189.55, 31,776.20 and 7,145.79

Step by Step Solution

1. Step 1: Write the proportion equation
   21,189.55 : 31,776.20 = 7,145.79 : x
2. Step 2: Convert to fraction form
   21,189.55/31,776.20 = 7,145.79/x
3. Step 3: Cross multiply
   21,189.55x = 31,776.20 × 7,145.79
4. Step 4: Simplify right side
   21,189.55x = 227,066,052.20
5. Step 5: Solve for x
   x = 227,066,052.20/21,189.55
6. Step 6: Final answer
   x = 10,715.94