Home / 820.80-1,229.64-511.20

Finding the Fourth Proportional to 820.80, 1,229.64 and 511.20

Calculator

Solution

The fourth proportional to 820.80, 1,229.64 and 511.20 is: 765.83

Step by Step Solution

  1. Step 1: Write the proportion equation
    820.80 : 1,229.64 = 511.20 : x
  2. Step 2: Convert to fraction form
    820.80/1,229.64 = 511.20/x
  3. Step 3: Cross multiply
    820.80x = 1,229.64 × 511.20
  4. Step 4: Simplify right side
    820.80x = 628,591.97
  5. Step 5: Solve for x
    x = 628,591.97/820.80
  6. Step 6: Final answer
    x = 765.83

Related Problems

Find fourth proportional to 410.40, 614.82 and 255.60
Half scale
Find fourth proportional to 1,641.60, 2,459.28 and 1,022.40
Double scale
Find fourth proportional to 821.80, 1,231.14 and 512.20
Similar ratio
Find fourth proportional to 1,231.20, 1,844.46 and 766.80
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.