Finding the Fourth Proportional to 1,641.72, 2,264.88 and 978.21

Step by Step Solution

1. Step 1: Write the proportion equation
   1,641.72 : 2,264.88 = 978.21 : x
2. Step 2: Convert to fraction form
   1,641.72/2,264.88 = 978.21/x
3. Step 3: Cross multiply
   1,641.72x = 2,264.88 × 978.21
4. Step 4: Simplify right side
   1,641.72x = 2,215,528.26
5. Step 5: Solve for x
   x = 2,215,528.26/1,641.72
6. Step 6: Final answer
   x = 1,349.52