Finding the Fourth Proportional to 1,641.96, 2,264.90 and 978.40

Step by Step Solution

1. Step 1: Write the proportion equation
   1,641.96 : 2,264.90 = 978.40 : x
2. Step 2: Convert to fraction form
   1,641.96/2,264.90 = 978.40/x
3. Step 3: Cross multiply
   1,641.96x = 2,264.90 × 978.40
4. Step 4: Simplify right side
   1,641.96x = 2,215,978.16
5. Step 5: Solve for x
   x = 2,215,978.16/1,641.96
6. Step 6: Final answer
   x = 1,349.59