Home / 688-720

Finding the Third Proportional to 688 and 720

Calculator

Solution

The third proportional to 688 and 720 is: 753.49

Step by Step Solution

  1. Step 1: Write the proportion equation
    688 : 720 = 720 : x
  2. Step 2: Convert to fraction form
    688/720 = 720/x
  3. Step 3: Cross multiply
    688x = 720 × 720
  4. Step 4: Simplify right side
    688x = 518,400
  5. Step 5: Solve for x
    x = 518,400/688
  6. Step 6: Final answer
    x = 753.49

Related Problems

Find third proportional to 344 and 360
Half scale
Find third proportional to 1,376 and 1,440
Double scale
Find third proportional to 690 and 722
Similar ratio
Find third proportional to 1,032 and 1,080
1.5x scale

Why These Related Problems?

These problems maintain the same ratio (1.05) or explore similar proportional relationships. Practicing with related ratios helps build understanding of proportional relationships.