Finding the Fourth Proportional to 7,142.40, 10,707.78 and 2,985.50

Step by Step Solution

1. Step 1: Write the proportion equation
   7,142.40 : 10,707.78 = 2,985.50 : x
2. Step 2: Convert to fraction form
   7,142.40/10,707.78 = 2,985.50/x
3. Step 3: Cross multiply
   7,142.40x = 10,707.78 × 2,985.50
4. Step 4: Simplify right side
   7,142.40x = 31,968,023.65
5. Step 5: Solve for x
   x = 31,968,023.65/7,142.40
6. Step 6: Final answer
   x = 4,475.81