Finding the Fourth Proportional to 1,008.89, 1,513.34 and 278.53

Step by Step Solution

1. Step 1: Write the proportion equation
   1,008.89 : 1,513.34 = 278.53 : x
2. Step 2: Convert to fraction form
   1,008.89/1,513.34 = 278.53/x
3. Step 3: Cross multiply
   1,008.89x = 1,513.34 × 278.53
4. Step 4: Simplify right side
   1,008.89x = 421,502.33
5. Step 5: Solve for x
   x = 421,502.33/1,008.89
6. Step 6: Final answer
   x = 417.79