Home / 393-420

Finding the Third Proportional to 393 and 420

Calculator

Solution

The third proportional to 393 and 420 is: 448.85

Step by Step Solution

  1. Step 1: Write the proportion equation
    393 : 420 = 420 : x
  2. Step 2: Convert to fraction form
    393/420 = 420/x
  3. Step 3: Cross multiply
    393x = 420 × 420
  4. Step 4: Simplify right side
    393x = 176,400
  5. Step 5: Solve for x
    x = 176,400/393
  6. Step 6: Final answer
    x = 448.85

Related Problems

Find third proportional to 196.50 and 210
Half scale
Find third proportional to 786 and 840
Double scale
Find third proportional to 395 and 422
Similar ratio
Find third proportional to 589.50 and 630
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.