Home / 259.80-389.70-86.47

Finding the Fourth Proportional to 259.80, 389.70 and 86.47

Calculator

Solution

The fourth proportional to 259.80, 389.70 and 86.47 is: 129.70

Step by Step Solution

  1. Step 1: Write the proportion equation
    259.80 : 389.70 = 86.47 : x
  2. Step 2: Convert to fraction form
    259.80/389.70 = 86.47/x
  3. Step 3: Cross multiply
    259.80x = 389.70 × 86.47
  4. Step 4: Simplify right side
    259.80x = 33,697.04
  5. Step 5: Solve for x
    x = 33,697.04/259.80
  6. Step 6: Final answer
    x = 129.70

Related Problems

Find fourth proportional to 129.90, 194.85 and 43.23
Half scale
Find fourth proportional to 519.60, 779.41 and 172.94
Double scale
Find fourth proportional to 260.80, 391.20 and 87.47
Similar ratio
Find fourth proportional to 389.70, 584.56 and 129.70
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.