Finding the Fourth Proportional to 1,641.72, 2,264.61 and 978.81

Step by Step Solution

1. Step 1: Write the proportion equation
   1,641.72 : 2,264.61 = 978.81 : x
2. Step 2: Convert to fraction form
   1,641.72/2,264.61 = 978.81/x
3. Step 3: Cross multiply
   1,641.72x = 2,264.61 × 978.81
4. Step 4: Simplify right side
   1,641.72x = 2,216,622.91
5. Step 5: Solve for x
   x = 2,216,622.91/1,641.72
6. Step 6: Final answer
   x = 1,350.18