Home / 18.90-28.31-12.11

Finding the Fourth Proportional to 18.90, 28.31 and 12.11

Calculator

Solution

The fourth proportional to 18.90, 28.31 and 12.11 is: 18.13

Step by Step Solution

  1. Step 1: Write the proportion equation
    18.90 : 28.31 = 12.11 : x
  2. Step 2: Convert to fraction form
    18.90/28.31 = 12.11/x
  3. Step 3: Cross multiply
    18.90x = 28.31 × 12.11
  4. Step 4: Simplify right side
    18.90x = 342.63
  5. Step 5: Solve for x
    x = 342.63/18.90
  6. Step 6: Final answer
    x = 18.13

Related Problems

Find fourth proportional to 9.45, 14.15 and 6.05
Half scale
Find fourth proportional to 37.80, 56.61 and 24.21
Double scale
Find fourth proportional to 19.90, 29.80 and 13.11
Similar ratio
Find fourth proportional to 28.35, 42.46 and 18.16
1.5x scale

Why These Related Problems?

These problems maintain the same ratio (1.50) or explore similar proportional relationships. Practicing with related ratios helps build understanding of proportional relationships.