Home / 399.75-643.50

Finding the Third Proportional to 399.75 and 643.50

Calculator

Solution

The third proportional to 399.75 and 643.50 is: 1,035.88

Step by Step Solution

  1. Step 1: Write the proportion equation
    399.75 : 643.50 = 643.50 : x
  2. Step 2: Convert to fraction form
    399.75/643.50 = 643.50/x
  3. Step 3: Cross multiply
    399.75x = 643.50 × 643.50
  4. Step 4: Simplify right side
    399.75x = 414,092.25
  5. Step 5: Solve for x
    x = 414,092.25/399.75
  6. Step 6: Final answer
    x = 1,035.88

Related Problems

Find third proportional to 199.88 and 321.75
Half scale
Find third proportional to 799.50 and 1,287
Double scale
Find third proportional to 402 and 647
Similar ratio
Find third proportional to 599.63 and 965.25
1.5x scale

Why These Related Problems?

These problems maintain the same ratio (1.61) or explore similar proportional relationships. Practicing with related ratios helps build understanding of proportional relationships.