Home / 630-840

Finding the Third Proportional to 630 and 840

Calculator

Solution

The third proportional to 630 and 840 is: 1,120

Step by Step Solution

  1. Step 1: Write the proportion equation
    630 : 840 = 840 : x
  2. Step 2: Convert to fraction form
    630/840 = 840/x
  3. Step 3: Cross multiply
    630x = 840 × 840
  4. Step 4: Simplify right side
    630x = 705,600
  5. Step 5: Solve for x
    x = 705,600/630
  6. Step 6: Final answer
    x = 1,120

Related Problems

Find third proportional to 315 and 420
Half scale
Find third proportional to 1,260 and 1,680
Double scale
Find third proportional to 632 and 843
Similar ratio
Find third proportional to 945 and 1,260
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.