Home / 79.40-109.45-61.89

Finding the Fourth Proportional to 79.40, 109.45 and 61.89

Calculator

Solution

The fourth proportional to 79.40, 109.45 and 61.89 is: 85.31

Step by Step Solution

  1. Step 1: Write the proportion equation
    79.40 : 109.45 = 61.89 : x
  2. Step 2: Convert to fraction form
    79.40/109.45 = 61.89/x
  3. Step 3: Cross multiply
    79.40x = 109.45 × 61.89
  4. Step 4: Simplify right side
    79.40x = 6,773.86
  5. Step 5: Solve for x
    x = 6,773.86/79.40
  6. Step 6: Final answer
    x = 85.31

Related Problems

Find fourth proportional to 39.70, 54.73 and 30.95
Half scale
Find fourth proportional to 158.80, 218.90 and 123.78
Double scale
Find fourth proportional to 80.40, 110.83 and 62.89
Similar ratio
Find fourth proportional to 119.10, 164.18 and 92.84
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.