Finding the Third Proportional to 810.50 and 890.50

Step by Step Solution

1. Step 1: Write the proportion equation
   810.50 : 890.50 = 890.50 : x
2. Step 2: Convert to fraction form
   810.50/890.50 = 890.50/x
3. Step 3: Cross multiply
   810.50x = 890.50 × 890.50
4. Step 4: Simplify right side
   810.50x = 792,990.25
5. Step 5: Solve for x
   x = 792,990.25/810.50
6. Step 6: Final answer
   x = 978.40