Home / 280.73-421.11-85.78

Finding the Fourth Proportional to 280.73, 421.11 and 85.78

Calculator

Solution

The fourth proportional to 280.73, 421.11 and 85.78 is: 128.68

Step by Step Solution

  1. Step 1: Write the proportion equation
    280.73 : 421.11 = 85.78 : x
  2. Step 2: Convert to fraction form
    280.73/421.11 = 85.78/x
  3. Step 3: Cross multiply
    280.73x = 421.11 × 85.78
  4. Step 4: Simplify right side
    280.73x = 36,123.34
  5. Step 5: Solve for x
    x = 36,123.34/280.73
  6. Step 6: Final answer
    x = 128.68

Related Problems

Find fourth proportional to 140.37, 210.56 and 42.89
Half scale
Find fourth proportional to 561.47, 842.22 and 171.56
Double scale
Find fourth proportional to 281.73, 422.61 and 86.78
Similar ratio
Find fourth proportional to 421.10, 631.67 and 128.67
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.