Finding the Fourth Proportional to 1,287.40, 1,774 and 1,054.12

Step by Step Solution

1. Step 1: Write the proportion equation
   1,287.40 : 1,774 = 1,054.12 : x
2. Step 2: Convert to fraction form
   1,287.40/1,774 = 1,054.12/x
3. Step 3: Cross multiply
   1,287.40x = 1,774 × 1,054.12
4. Step 4: Simplify right side
   1,287.40x = 1,870,008.88
5. Step 5: Solve for x
   x = 1,870,008.88/1,287.40
6. Step 6: Final answer
   x = 1,452.55