Home / 22.31-30.78-21.90

Finding the Fourth Proportional to 22.31, 30.78 and 21.90

Calculator

Solution

The fourth proportional to 22.31, 30.78 and 21.90 is: 30.22

Step by Step Solution

  1. Step 1: Write the proportion equation
    22.31 : 30.78 = 21.90 : x
  2. Step 2: Convert to fraction form
    22.31/30.78 = 21.90/x
  3. Step 3: Cross multiply
    22.31x = 30.78 × 21.90
  4. Step 4: Simplify right side
    22.31x = 674.20
  5. Step 5: Solve for x
    x = 674.20/22.31
  6. Step 6: Final answer
    x = 30.22

Related Problems

Find fourth proportional to 11.15, 15.39 and 10.95
Half scale
Find fourth proportional to 44.62, 61.56 and 43.81
Double scale
Find fourth proportional to 23.31, 32.16 and 22.90
Similar ratio
Find fourth proportional to 33.46, 46.17 and 32.86
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.