Finding the Fourth Proportional to 1,089.72, 1,635.18 and 918.42

Step by Step Solution

1. Step 1: Write the proportion equation
   1,089.72 : 1,635.18 = 918.42 : x
2. Step 2: Convert to fraction form
   1,089.72/1,635.18 = 918.42/x
3. Step 3: Cross multiply
   1,089.72x = 1,635.18 × 918.42
4. Step 4: Simplify right side
   1,089.72x = 1,501,782.02
5. Step 5: Solve for x
   x = 1,501,782.02/1,089.72
6. Step 6: Final answer
   x = 1,378.14