Home / 261-391

Finding the Third Proportional to 261 and 391

Calculator

Solution

The third proportional to 261 and 391 is: 585.75

Step by Step Solution

  1. Step 1: Write the proportion equation
    261 : 391 = 391 : x
  2. Step 2: Convert to fraction form
    261/391 = 391/x
  3. Step 3: Cross multiply
    261x = 391 × 391
  4. Step 4: Simplify right side
    261x = 152,881
  5. Step 5: Solve for x
    x = 152,881/261
  6. Step 6: Final answer
    x = 585.75

Related Problems

Find third proportional to 130.50 and 195.50
Half scale
Find third proportional to 522 and 782
Double scale
Find third proportional to 263 and 394
Similar ratio
Find third proportional to 391.50 and 586.50
1.5x scale

Why These Related Problems?

These problems maintain the same ratio (1.50) or explore similar proportional relationships. Practicing with related ratios helps build understanding of proportional relationships.