Home / 420.50-640.75

Finding the Third Proportional to 420.50 and 640.75

Calculator

Solution

The third proportional to 420.50 and 640.75 is: 976.36

Step by Step Solution

  1. Step 1: Write the proportion equation
    420.50 : 640.75 = 640.75 : x
  2. Step 2: Convert to fraction form
    420.50/640.75 = 640.75/x
  3. Step 3: Cross multiply
    420.50x = 640.75 × 640.75
  4. Step 4: Simplify right side
    420.50x = 410,560.56
  5. Step 5: Solve for x
    x = 410,560.56/420.50
  6. Step 6: Final answer
    x = 976.36

Related Problems

Find third proportional to 210.25 and 320.38
Half scale
Find third proportional to 841 and 1,281.50
Double scale
Find third proportional to 423 and 644
Similar ratio
Find third proportional to 630.75 and 961.13
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.