Home / 421.50-642

Finding the Third Proportional to 421.50 and 642

Calculator

Solution

The third proportional to 421.50 and 642 is: 977.85

Step by Step Solution

  1. Step 1: Write the proportion equation
    421.50 : 642 = 642 : x
  2. Step 2: Convert to fraction form
    421.50/642 = 642/x
  3. Step 3: Cross multiply
    421.50x = 642 × 642
  4. Step 4: Simplify right side
    421.50x = 412,164
  5. Step 5: Solve for x
    x = 412,164/421.50
  6. Step 6: Final answer
    x = 977.85

Related Problems

Find third proportional to 210.75 and 321
Half scale
Find third proportional to 843 and 1,284
Double scale
Find third proportional to 424 and 645
Similar ratio
Find third proportional to 632.25 and 963
1.5x scale

Why These Related Problems?

These problems maintain the same ratio (1.52) or explore similar proportional relationships. Practicing with related ratios helps build understanding of proportional relationships.