Finding the Fourth Proportional to 1,420.91, 1,960.11 and 978.05

Step by Step Solution

1. Step 1: Write the proportion equation
   1,420.91 : 1,960.11 = 978.05 : x
2. Step 2: Convert to fraction form
   1,420.91/1,960.11 = 978.05/x
3. Step 3: Cross multiply
   1,420.91x = 1,960.11 × 978.05
4. Step 4: Simplify right side
   1,420.91x = 1,917,070.89
5. Step 5: Solve for x
   x = 1,917,070.89/1,420.91
6. Step 6: Final answer
   x = 1,349.19