Home / 291-640

Finding the Third Proportional to 291 and 640

Calculator

Solution

The third proportional to 291 and 640 is: 1,407.56

Step by Step Solution

  1. Step 1: Write the proportion equation
    291 : 640 = 640 : x
  2. Step 2: Convert to fraction form
    291/640 = 640/x
  3. Step 3: Cross multiply
    291x = 640 × 640
  4. Step 4: Simplify right side
    291x = 409,600
  5. Step 5: Solve for x
    x = 409,600/291
  6. Step 6: Final answer
    x = 1,407.56

Related Problems

Find third proportional to 145.50 and 320
Half scale
Find third proportional to 582 and 1,280
Double scale
Find third proportional to 293 and 644
Similar ratio
Find third proportional to 436.50 and 960
1.5x scale

Why These Related Problems?

These problems maintain the same ratio (2.20) or explore similar proportional relationships. Practicing with related ratios helps build understanding of proportional relationships.