Finding the Fourth Proportional to 1,172.42, 1,616.31 and 840.25

Step by Step Solution

1. Step 1: Write the proportion equation
   1,172.42 : 1,616.31 = 840.25 : x
2. Step 2: Convert to fraction form
   1,172.42/1,616.31 = 840.25/x
3. Step 3: Cross multiply
   1,172.42x = 1,616.31 × 840.25
4. Step 4: Simplify right side
   1,172.42x = 1,358,104.48
5. Step 5: Solve for x
   x = 1,358,104.48/1,172.42
6. Step 6: Final answer
   x = 1,158.38