Home / 639.75-879.75

Finding the Third Proportional to 639.75 and 879.75

Calculator

Solution

The third proportional to 639.75 and 879.75 is: 1,209.79

Step by Step Solution

  1. Step 1: Write the proportion equation
    639.75 : 879.75 = 879.75 : x
  2. Step 2: Convert to fraction form
    639.75/879.75 = 879.75/x
  3. Step 3: Cross multiply
    639.75x = 879.75 × 879.75
  4. Step 4: Simplify right side
    639.75x = 773,960.06
  5. Step 5: Solve for x
    x = 773,960.06/639.75
  6. Step 6: Final answer
    x = 1,209.79

Related Problems

Find third proportional to 319.88 and 439.88
Half scale
Find third proportional to 1,279.50 and 1,759.50
Double scale
Find third proportional to 642 and 883
Similar ratio
Find third proportional to 959.63 and 1,319.63
1.5x scale

Why These Related Problems?

These problems maintain the same ratio (1.38) or explore similar proportional relationships. Practicing with related ratios helps build understanding of proportional relationships.