Home / 545.20-817.80-390.80

Finding the Fourth Proportional to 545.20, 817.80 and 390.80

Calculator

Solution

The fourth proportional to 545.20, 817.80 and 390.80 is: 586.20

Step by Step Solution

  1. Step 1: Write the proportion equation
    545.20 : 817.80 = 390.80 : x
  2. Step 2: Convert to fraction form
    545.20/817.80 = 390.80/x
  3. Step 3: Cross multiply
    545.20x = 817.80 × 390.80
  4. Step 4: Simplify right side
    545.20x = 319,596.24
  5. Step 5: Solve for x
    x = 319,596.24/545.20
  6. Step 6: Final answer
    x = 586.20

Related Problems

Find fourth proportional to 272.60, 408.90 and 195.40
Half scale
Find fourth proportional to 1,090.40, 1,635.60 and 781.60
Double scale
Find fourth proportional to 546.20, 819.30 and 391.80
Similar ratio
Find fourth proportional to 817.80, 1,226.70 and 586.20
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.