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Finding the Fourth Proportional to 811.30, 1,215.15 and 426.10

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Solution

The fourth proportional to 811.30, 1,215.15 and 426.10 is: 638.20

Step by Step Solution

  1. Step 1: Write the proportion equation
    811.30 : 1,215.15 = 426.10 : x
  2. Step 2: Convert to fraction form
    811.30/1,215.15 = 426.10/x
  3. Step 3: Cross multiply
    811.30x = 1,215.15 × 426.10
  4. Step 4: Simplify right side
    811.30x = 517,775.42
  5. Step 5: Solve for x
    x = 517,775.42/811.30
  6. Step 6: Final answer
    x = 638.20

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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.