Finding the Fourth Proportional to 1,421.73, 1,961.51 and 978.84

Step by Step Solution

1. Step 1: Write the proportion equation
   1,421.73 : 1,961.51 = 978.84 : x
2. Step 2: Convert to fraction form
   1,421.73/1,961.51 = 978.84/x
3. Step 3: Cross multiply
   1,421.73x = 1,961.51 × 978.84
4. Step 4: Simplify right side
   1,421.73x = 1,919,999.55
5. Step 5: Solve for x
   x = 1,919,999.55/1,421.73
6. Step 6: Final answer
   x = 1,350.47