Home / 390-514.50

Finding the Third Proportional to 390 and 514.50

Calculator

Solution

The third proportional to 390 and 514.50 is: 678.74

Step by Step Solution

  1. Step 1: Write the proportion equation
    390 : 514.50 = 514.50 : x
  2. Step 2: Convert to fraction form
    390/514.50 = 514.50/x
  3. Step 3: Cross multiply
    390x = 514.50 × 514.50
  4. Step 4: Simplify right side
    390x = 264,710.25
  5. Step 5: Solve for x
    x = 264,710.25/390
  6. Step 6: Final answer
    x = 678.74

Related Problems

Find third proportional to 195 and 257.25
Half scale
Find third proportional to 780 and 1,029
Double scale
Find third proportional to 392 and 517
Similar ratio
Find third proportional to 585 and 771.75
1.5x scale

Why These Related Problems?

These problems maintain the same ratio (1.32) or explore similar proportional relationships. Practicing with related ratios helps build understanding of proportional relationships.