Home / 128-199

Finding the Third Proportional to 128 and 199

Calculator

Solution

The third proportional to 128 and 199 is: 309.38

Step by Step Solution

  1. Step 1: Write the proportion equation
    128 : 199 = 199 : x
  2. Step 2: Convert to fraction form
    128/199 = 199/x
  3. Step 3: Cross multiply
    128x = 199 × 199
  4. Step 4: Simplify right side
    128x = 39,601
  5. Step 5: Solve for x
    x = 39,601/128
  6. Step 6: Final answer
    x = 309.38

Related Problems

Find third proportional to 64 and 99.50
Half scale
Find third proportional to 256 and 398
Double scale
Find third proportional to 130 and 202
Similar ratio
Find third proportional to 192 and 298.50
1.5x scale

Why These Related Problems?

These problems maintain the same ratio (1.55) or explore similar proportional relationships. Practicing with related ratios helps build understanding of proportional relationships.