Finding the Fourth Proportional to 1,421.29, 1,960.63 and 978.42

Step by Step Solution

1. Step 1: Write the proportion equation
   1,421.29 : 1,960.63 = 978.42 : x
2. Step 2: Convert to fraction form
   1,421.29/1,960.63 = 978.42/x
3. Step 3: Cross multiply
   1,421.29x = 1,960.63 × 978.42
4. Step 4: Simplify right side
   1,421.29x = 1,918,314.71
5. Step 5: Solve for x
   x = 1,918,314.71/1,421.29
6. Step 6: Final answer
   x = 1,349.70