Finding the Fourth Proportional to 1,086.19, 1,627.59 and 840

Step by Step Solution

1. Step 1: Write the proportion equation
   1,086.19 : 1,627.59 = 840 : x
2. Step 2: Convert to fraction form
   1,086.19/1,627.59 = 840/x
3. Step 3: Cross multiply
   1,086.19x = 1,627.59 × 840
4. Step 4: Simplify right side
   1,086.19x = 1,367,175.60
5. Step 5: Solve for x
   x = 1,367,175.60/1,086.19
6. Step 6: Final answer
   x = 1,258.69