Home / 27.72-38.21-20.78

Finding the Fourth Proportional to 27.72, 38.21 and 20.78

Calculator

Solution

The fourth proportional to 27.72, 38.21 and 20.78 is: 28.65

Step by Step Solution

  1. Step 1: Write the proportion equation
    27.72 : 38.21 = 20.78 : x
  2. Step 2: Convert to fraction form
    27.72/38.21 = 20.78/x
  3. Step 3: Cross multiply
    27.72x = 38.21 × 20.78
  4. Step 4: Simplify right side
    27.72x = 794.05
  5. Step 5: Solve for x
    x = 794.05/27.72
  6. Step 6: Final answer
    x = 28.65

Related Problems

Find fourth proportional to 13.86, 19.10 and 10.39
Half scale
Find fourth proportional to 55.43, 76.42 and 41.56
Double scale
Find fourth proportional to 28.72, 39.59 and 21.78
Similar ratio
Find fourth proportional to 41.58, 57.31 and 31.17
1.5x scale

Why These Related Problems?

These problems maintain the same ratio (1.38) or explore similar proportional relationships. Practicing with related ratios helps build understanding of proportional relationships.