Home / 489-621

Finding the Third Proportional to 489 and 621

Calculator

Solution

The third proportional to 489 and 621 is: 788.63

Step by Step Solution

  1. Step 1: Write the proportion equation
    489 : 621 = 621 : x
  2. Step 2: Convert to fraction form
    489/621 = 621/x
  3. Step 3: Cross multiply
    489x = 621 × 621
  4. Step 4: Simplify right side
    489x = 385,641
  5. Step 5: Solve for x
    x = 385,641/489
  6. Step 6: Final answer
    x = 788.63

Related Problems

Find third proportional to 244.50 and 310.50
Half scale
Find third proportional to 978 and 1,242
Double scale
Find third proportional to 491 and 624
Similar ratio
Find third proportional to 733.50 and 931.50
1.5x scale

Why These Related Problems?

These problems maintain the same ratio (1.27) or explore similar proportional relationships. Practicing with related ratios helps build understanding of proportional relationships.