Finding the Fourth Proportional to 1,388.21, 1,915.67 and 829.05

Step by Step Solution

1. Step 1: Write the proportion equation
   1,388.21 : 1,915.67 = 829.05 : x
2. Step 2: Convert to fraction form
   1,388.21/1,915.67 = 829.05/x
3. Step 3: Cross multiply
   1,388.21x = 1,915.67 × 829.05
4. Step 4: Simplify right side
   1,388.21x = 1,588,182.07
5. Step 5: Solve for x
   x = 1,588,182.07/1,388.21
6. Step 6: Final answer
   x = 1,144.05