Home / 290-421

Finding the Third Proportional to 290 and 421

Calculator

Solution

The third proportional to 290 and 421 is: 611.18

Step by Step Solution

  1. Step 1: Write the proportion equation
    290 : 421 = 421 : x
  2. Step 2: Convert to fraction form
    290/421 = 421/x
  3. Step 3: Cross multiply
    290x = 421 × 421
  4. Step 4: Simplify right side
    290x = 177,241
  5. Step 5: Solve for x
    x = 177,241/290
  6. Step 6: Final answer
    x = 611.18

Related Problems

Find third proportional to 145 and 210.50
Half scale
Find third proportional to 580 and 842
Double scale
Find third proportional to 292 and 424
Similar ratio
Find third proportional to 435 and 631.50
1.5x scale

Why These Related Problems?

These problems maintain the same ratio (1.45) or explore similar proportional relationships. Practicing with related ratios helps build understanding of proportional relationships.