Finding the Fourth Proportional to 918.72, 1,371.42 and 763.20

Step by Step Solution

1. Step 1: Write the proportion equation
   918.72 : 1,371.42 = 763.20 : x
2. Step 2: Convert to fraction form
   918.72/1,371.42 = 763.20/x
3. Step 3: Cross multiply
   918.72x = 1,371.42 × 763.20
4. Step 4: Simplify right side
   918.72x = 1,046,667.74
5. Step 5: Solve for x
   x = 1,046,667.74/918.72
6. Step 6: Final answer
   x = 1,139.27