Finding the Fourth Proportional to 1,389.50, 1,917.50 and 830.22

Step by Step Solution

1. Step 1: Write the proportion equation
   1,389.50 : 1,917.50 = 830.22 : x
2. Step 2: Convert to fraction form
   1,389.50/1,917.50 = 830.22/x
3. Step 3: Cross multiply
   1,389.50x = 1,917.50 × 830.22
4. Step 4: Simplify right side
   1,389.50x = 1,591,946.85
5. Step 5: Solve for x
   x = 1,591,946.85/1,389.50
6. Step 6: Final answer
   x = 1,145.70