Home / 509-643

Finding the Third Proportional to 509 and 643

Calculator

Solution

The third proportional to 509 and 643 is: 812.28

Step by Step Solution

  1. Step 1: Write the proportion equation
    509 : 643 = 643 : x
  2. Step 2: Convert to fraction form
    509/643 = 643/x
  3. Step 3: Cross multiply
    509x = 643 × 643
  4. Step 4: Simplify right side
    509x = 413,449
  5. Step 5: Solve for x
    x = 413,449/509
  6. Step 6: Final answer
    x = 812.28

Related Problems

Find third proportional to 254.50 and 321.50
Half scale
Find third proportional to 1,018 and 1,286
Double scale
Find third proportional to 511 and 646
Similar ratio
Find third proportional to 763.50 and 964.50
1.5x scale

Why These Related Problems?

These problems maintain the same ratio (1.26) or explore similar proportional relationships. Practicing with related ratios helps build understanding of proportional relationships.