Home / 391-647

Finding the Third Proportional to 391 and 647

Calculator

Solution

The third proportional to 391 and 647 is: 1,070.61

Step by Step Solution

  1. Step 1: Write the proportion equation
    391 : 647 = 647 : x
  2. Step 2: Convert to fraction form
    391/647 = 647/x
  3. Step 3: Cross multiply
    391x = 647 × 647
  4. Step 4: Simplify right side
    391x = 418,609
  5. Step 5: Solve for x
    x = 418,609/391
  6. Step 6: Final answer
    x = 1,070.61

Related Problems

Find third proportional to 195.50 and 323.50
Half scale
Find third proportional to 782 and 1,294
Double scale
Find third proportional to 393 and 650
Similar ratio
Find third proportional to 586.50 and 970.50
1.5x scale

Why These Related Problems?

These problems maintain the same ratio (1.65) or explore similar proportional relationships. Practicing with related ratios helps build understanding of proportional relationships.