Finding the Fourth Proportional to 1,009.10, 1,513.59 and 278.72

Step by Step Solution

1. Step 1: Write the proportion equation
   1,009.10 : 1,513.59 = 278.72 : x
2. Step 2: Convert to fraction form
   1,009.10/1,513.59 = 278.72/x
3. Step 3: Cross multiply
   1,009.10x = 1,513.59 × 278.72
4. Step 4: Simplify right side
   1,009.10x = 421,867.80
5. Step 5: Solve for x
   x = 421,867.80/1,009.10
6. Step 6: Final answer
   x = 418.06