Home / 490-643

Finding the Third Proportional to 490 and 643

Calculator

Solution

The third proportional to 490 and 643 is: 843.77

Step by Step Solution

  1. Step 1: Write the proportion equation
    490 : 643 = 643 : x
  2. Step 2: Convert to fraction form
    490/643 = 643/x
  3. Step 3: Cross multiply
    490x = 643 × 643
  4. Step 4: Simplify right side
    490x = 413,449
  5. Step 5: Solve for x
    x = 413,449/490
  6. Step 6: Final answer
    x = 843.77

Related Problems

Find third proportional to 245 and 321.50
Half scale
Find third proportional to 980 and 1,286
Double scale
Find third proportional to 492 and 646
Similar ratio
Find third proportional to 735 and 964.50
1.5x scale

Why These Related Problems?

These problems maintain the same ratio (1.31) or explore similar proportional relationships. Practicing with related ratios helps build understanding of proportional relationships.