Finding the Fourth Proportional to 1,538.79, 2,122.72 and 978.30

Step by Step Solution

1. Step 1: Write the proportion equation
   1,538.79 : 2,122.72 = 978.30 : x
2. Step 2: Convert to fraction form
   1,538.79/2,122.72 = 978.30/x
3. Step 3: Cross multiply
   1,538.79x = 2,122.72 × 978.30
4. Step 4: Simplify right side
   1,538.79x = 2,076,656.98
5. Step 5: Solve for x
   x = 2,076,656.98/1,538.79
6. Step 6: Final answer
   x = 1,349.54