Home / 356-420

Finding the Third Proportional to 356 and 420

Calculator

Solution

The third proportional to 356 and 420 is: 495.51

Step by Step Solution

  1. Step 1: Write the proportion equation
    356 : 420 = 420 : x
  2. Step 2: Convert to fraction form
    356/420 = 420/x
  3. Step 3: Cross multiply
    356x = 420 × 420
  4. Step 4: Simplify right side
    356x = 176,400
  5. Step 5: Solve for x
    x = 176,400/356
  6. Step 6: Final answer
    x = 495.51

Related Problems

Find third proportional to 178 and 210
Half scale
Find third proportional to 712 and 840
Double scale
Find third proportional to 358 and 422
Similar ratio
Find third proportional to 534 and 630
1.5x scale

Why These Related Problems?

These problems maintain the same ratio (1.18) or explore similar proportional relationships. Practicing with related ratios helps build understanding of proportional relationships.