Home / 278.70-417.90-86.28

Finding the Fourth Proportional to 278.70, 417.90 and 86.28

Calculator

Solution

The fourth proportional to 278.70, 417.90 and 86.28 is: 129.37

Step by Step Solution

  1. Step 1: Write the proportion equation
    278.70 : 417.90 = 86.28 : x
  2. Step 2: Convert to fraction form
    278.70/417.90 = 86.28/x
  3. Step 3: Cross multiply
    278.70x = 417.90 × 86.28
  4. Step 4: Simplify right side
    278.70x = 36,056.41
  5. Step 5: Solve for x
    x = 36,056.41/278.70
  6. Step 6: Final answer
    x = 129.37

Related Problems

Find fourth proportional to 139.35, 208.95 and 43.14
Half scale
Find fourth proportional to 557.40, 835.80 and 172.56
Double scale
Find fourth proportional to 279.70, 419.40 and 87.28
Similar ratio
Find fourth proportional to 418.05, 626.85 and 129.42
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.