Finding the Fourth Proportional to 1,272.16, 1,756.40 and 800.72

Step by Step Solution

1. Step 1: Write the proportion equation
   1,272.16 : 1,756.40 = 800.72 : x
2. Step 2: Convert to fraction form
   1,272.16/1,756.40 = 800.72/x
3. Step 3: Cross multiply
   1,272.16x = 1,756.40 × 800.72
4. Step 4: Simplify right side
   1,272.16x = 1,406,384.61
5. Step 5: Solve for x
   x = 1,406,384.61/1,272.16
6. Step 6: Final answer
   x = 1,105.51