Finding the Third Proportional to 991.50 and 1,398

Step by Step Solution

1. Step 1: Write the proportion equation
   991.50 : 1,398 = 1,398 : x
2. Step 2: Convert to fraction form
   991.50/1,398 = 1,398/x
3. Step 3: Cross multiply
   991.50x = 1,398 × 1,398
4. Step 4: Simplify right side
   991.50x = 1,954,404
5. Step 5: Solve for x
   x = 1,954,404/991.50
6. Step 6: Final answer
   x = 1,971.16