Home / 28.20-42.30-7.91

Finding the Fourth Proportional to 28.20, 42.30 and 7.91

Calculator

Solution

The fourth proportional to 28.20, 42.30 and 7.91 is: 11.86

Step by Step Solution

  1. Step 1: Write the proportion equation
    28.20 : 42.30 = 7.91 : x
  2. Step 2: Convert to fraction form
    28.20/42.30 = 7.91/x
  3. Step 3: Cross multiply
    28.20x = 42.30 × 7.91
  4. Step 4: Simplify right side
    28.20x = 334.38
  5. Step 5: Solve for x
    x = 334.38/28.20
  6. Step 6: Final answer
    x = 11.86

Related Problems

Find fourth proportional to 14.10, 21.15 and 3.95
Half scale
Find fourth proportional to 56.40, 84.60 and 15.81
Double scale
Find fourth proportional to 29.20, 43.80 and 8.91
Similar ratio
Find fourth proportional to 42.30, 63.45 and 11.86
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.