Finding the Fourth Proportional to 978.60, 1,347.12 and 828.48

Step by Step Solution

1. Step 1: Write the proportion equation
   978.60 : 1,347.12 = 828.48 : x
2. Step 2: Convert to fraction form
   978.60/1,347.12 = 828.48/x
3. Step 3: Cross multiply
   978.60x = 1,347.12 × 828.48
4. Step 4: Simplify right side
   978.60x = 1,116,061.98
5. Step 5: Solve for x
   x = 1,116,061.98/978.60
6. Step 6: Final answer
   x = 1,140.47