Home / 1,281.40-1,920.30-511

Finding the Fourth Proportional to 1,281.40, 1,920.30 and 511

Calculator

Solution

The fourth proportional to 1,281.40, 1,920.30 and 511 is: 765.78

Step by Step Solution

  1. Step 1: Write the proportion equation
    1,281.40 : 1,920.30 = 511 : x
  2. Step 2: Convert to fraction form
    1,281.40/1,920.30 = 511/x
  3. Step 3: Cross multiply
    1,281.40x = 1,920.30 × 511
  4. Step 4: Simplify right side
    1,281.40x = 981,273.30
  5. Step 5: Solve for x
    x = 981,273.30/1,281.40
  6. Step 6: Final answer
    x = 765.78

Related Problems

Find fourth proportional to 640.70, 960.15 and 255.50
Half scale
Find fourth proportional to 2,562.80, 3,840.60 and 1,022
Double scale
Find fourth proportional to 1,282.40, 1,921.80 and 512
Similar ratio
Find fourth proportional to 1,922.10, 2,880.45 and 766.50
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.