Home / 317-421

Finding the Third Proportional to 317 and 421

Calculator

Solution

The third proportional to 317 and 421 is: 559.12

Step by Step Solution

  1. Step 1: Write the proportion equation
    317 : 421 = 421 : x
  2. Step 2: Convert to fraction form
    317/421 = 421/x
  3. Step 3: Cross multiply
    317x = 421 × 421
  4. Step 4: Simplify right side
    317x = 177,241
  5. Step 5: Solve for x
    x = 177,241/317
  6. Step 6: Final answer
    x = 559.12

Related Problems

Find third proportional to 158.50 and 210.50
Half scale
Find third proportional to 634 and 842
Double scale
Find third proportional to 319 and 424
Similar ratio
Find third proportional to 475.50 and 631.50
1.5x scale

Why These Related Problems?

These problems maintain the same ratio (1.33) or explore similar proportional relationships. Practicing with related ratios helps build understanding of proportional relationships.