Home / 342-390

Finding the Third Proportional to 342 and 390

Calculator

Solution

The third proportional to 342 and 390 is: 444.74

Step by Step Solution

  1. Step 1: Write the proportion equation
    342 : 390 = 390 : x
  2. Step 2: Convert to fraction form
    342/390 = 390/x
  3. Step 3: Cross multiply
    342x = 390 × 390
  4. Step 4: Simplify right side
    342x = 152,100
  5. Step 5: Solve for x
    x = 152,100/342
  6. Step 6: Final answer
    x = 444.74

Related Problems

Find third proportional to 171 and 195
Half scale
Find third proportional to 684 and 780
Double scale
Find third proportional to 344 and 392
Similar ratio
Find third proportional to 513 and 585
1.5x scale

Why These Related Problems?

These problems maintain the same ratio (1.14) or explore similar proportional relationships. Practicing with related ratios helps build understanding of proportional relationships.