Home / 426.78-639.72-209.91

Finding the Fourth Proportional to 426.78, 639.72 and 209.91

Calculator

Solution

The fourth proportional to 426.78, 639.72 and 209.91 is: 314.64

Step by Step Solution

  1. Step 1: Write the proportion equation
    426.78 : 639.72 = 209.91 : x
  2. Step 2: Convert to fraction form
    426.78/639.72 = 209.91/x
  3. Step 3: Cross multiply
    426.78x = 639.72 × 209.91
  4. Step 4: Simplify right side
    426.78x = 134,283.63
  5. Step 5: Solve for x
    x = 134,283.63/426.78
  6. Step 6: Final answer
    x = 314.64

Related Problems

Find fourth proportional to 213.39, 319.86 and 104.96
Half scale
Find fourth proportional to 853.56, 1,279.44 and 419.82
Double scale
Find fourth proportional to 427.78, 641.22 and 210.91
Similar ratio
Find fourth proportional to 640.17, 959.58 and 314.87
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.