Home / 21-30.75

Finding the Third Proportional to 21 and 30.75

Calculator

Solution

The third proportional to 21 and 30.75 is: 45.03

Step by Step Solution

  1. Step 1: Write the proportion equation
    21 : 30.75 = 30.75 : x
  2. Step 2: Convert to fraction form
    21/30.75 = 30.75/x
  3. Step 3: Cross multiply
    21x = 30.75 × 30.75
  4. Step 4: Simplify right side
    21x = 945.56
  5. Step 5: Solve for x
    x = 945.56/21
  6. Step 6: Final answer
    x = 45.03

Related Problems

Find third proportional to 10.50 and 15.38
Half scale
Find third proportional to 42 and 61.50
Double scale
Find third proportional to 23 and 34
Similar ratio
Find third proportional to 31.50 and 46.13
1.5x scale

Why These Related Problems?

These problems maintain the same ratio (1.46) or explore similar proportional relationships. Practicing with related ratios helps build understanding of proportional relationships.