Home / 686.50-978

Finding the Third Proportional to 686.50 and 978

Calculator

Solution

The third proportional to 686.50 and 978 is: 1,393.28

Step by Step Solution

  1. Step 1: Write the proportion equation
    686.50 : 978 = 978 : x
  2. Step 2: Convert to fraction form
    686.50/978 = 978/x
  3. Step 3: Cross multiply
    686.50x = 978 × 978
  4. Step 4: Simplify right side
    686.50x = 956,484
  5. Step 5: Solve for x
    x = 956,484/686.50
  6. Step 6: Final answer
    x = 1,393.28

Related Problems

Find third proportional to 343.25 and 489
Half scale
Find third proportional to 1,373 and 1,956
Double scale
Find third proportional to 689 and 981
Similar ratio
Find third proportional to 1,029.75 and 1,467
1.5x scale

Why These Related Problems?

These problems maintain the same ratio (1.42) or explore similar proportional relationships. Practicing with related ratios helps build understanding of proportional relationships.