Home / 172.20-258.15-80.85

Finding the Fourth Proportional to 172.20, 258.15 and 80.85

Calculator

Solution

The fourth proportional to 172.20, 258.15 and 80.85 is: 121.20

Step by Step Solution

  1. Step 1: Write the proportion equation
    172.20 : 258.15 = 80.85 : x
  2. Step 2: Convert to fraction form
    172.20/258.15 = 80.85/x
  3. Step 3: Cross multiply
    172.20x = 258.15 × 80.85
  4. Step 4: Simplify right side
    172.20x = 20,871.43
  5. Step 5: Solve for x
    x = 20,871.43/172.20
  6. Step 6: Final answer
    x = 121.20

Related Problems

Find fourth proportional to 86.10, 129.08 and 40.43
Half scale
Find fourth proportional to 344.40, 516.30 and 161.70
Double scale
Find fourth proportional to 173.20, 259.65 and 81.85
Similar ratio
Find fourth proportional to 258.30, 387.23 and 121.28
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.