Finding the Fourth Proportional to 1,439.28, 1,985.40 and 972.72

Step by Step Solution

1. Step 1: Write the proportion equation
   1,439.28 : 1,985.40 = 972.72 : x
2. Step 2: Convert to fraction form
   1,439.28/1,985.40 = 972.72/x
3. Step 3: Cross multiply
   1,439.28x = 1,985.40 × 972.72
4. Step 4: Simplify right side
   1,439.28x = 1,931,238.29
5. Step 5: Solve for x
   x = 1,931,238.29/1,439.28
6. Step 6: Final answer
   x = 1,341.81