Home / 642-686

Finding the Third Proportional to 642 and 686

Calculator

Solution

The third proportional to 642 and 686 is: 733.02

Step by Step Solution

  1. Step 1: Write the proportion equation
    642 : 686 = 686 : x
  2. Step 2: Convert to fraction form
    642/686 = 686/x
  3. Step 3: Cross multiply
    642x = 686 × 686
  4. Step 4: Simplify right side
    642x = 470,596
  5. Step 5: Solve for x
    x = 470,596/642
  6. Step 6: Final answer
    x = 733.02

Related Problems

Find third proportional to 321 and 343
Half scale
Find third proportional to 1,284 and 1,372
Double scale
Find third proportional to 644 and 688
Similar ratio
Find third proportional to 963 and 1,029
1.5x scale

Why These Related Problems?

These problems maintain the same ratio (1.07) or explore similar proportional relationships. Practicing with related ratios helps build understanding of proportional relationships.