Home / 853.96-1,280.36-420.79

Finding the Fourth Proportional to 853.96, 1,280.36 and 420.79

Calculator

Solution

The fourth proportional to 853.96, 1,280.36 and 420.79 is: 630.90

Step by Step Solution

  1. Step 1: Write the proportion equation
    853.96 : 1,280.36 = 420.79 : x
  2. Step 2: Convert to fraction form
    853.96/1,280.36 = 420.79/x
  3. Step 3: Cross multiply
    853.96x = 1,280.36 × 420.79
  4. Step 4: Simplify right side
    853.96x = 538,760.58
  5. Step 5: Solve for x
    x = 538,760.58/853.96
  6. Step 6: Final answer
    x = 630.90

Related Problems

Find fourth proportional to 426.98, 640.18 and 210.40
Half scale
Find fourth proportional to 1,707.92, 2,560.71 and 841.58
Double scale
Find fourth proportional to 854.96, 1,281.85 and 421.79
Similar ratio
Find fourth proportional to 1,280.94, 1,920.53 and 631.19
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.