Finding the Fourth Proportional to 1,440.16, 1,987.20 and 842.72

Step by Step Solution

1. Step 1: Write the proportion equation
   1,440.16 : 1,987.20 = 842.72 : x
2. Step 2: Convert to fraction form
   1,440.16/1,987.20 = 842.72/x
3. Step 3: Cross multiply
   1,440.16x = 1,987.20 × 842.72
4. Step 4: Simplify right side
   1,440.16x = 1,674,653.18
5. Step 5: Solve for x
   x = 1,674,653.18/1,440.16
6. Step 6: Final answer
   x = 1,162.82