Home / 678.60-1,016.55-389.70

Finding the Fourth Proportional to 678.60, 1,016.55 and 389.70

Calculator

Solution

The fourth proportional to 678.60, 1,016.55 and 389.70 is: 583.77

Step by Step Solution

  1. Step 1: Write the proportion equation
    678.60 : 1,016.55 = 389.70 : x
  2. Step 2: Convert to fraction form
    678.60/1,016.55 = 389.70/x
  3. Step 3: Cross multiply
    678.60x = 1,016.55 × 389.70
  4. Step 4: Simplify right side
    678.60x = 396,149.54
  5. Step 5: Solve for x
    x = 396,149.54/678.60
  6. Step 6: Final answer
    x = 583.77

Related Problems

Find fourth proportional to 339.30, 508.28 and 194.85
Half scale
Find fourth proportional to 1,357.20, 2,033.10 and 779.40
Double scale
Find fourth proportional to 679.60, 1,018.05 and 390.70
Similar ratio
Find fourth proportional to 1,017.90, 1,524.83 and 584.55
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.