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Finding the Fourth Proportional to 813.81, 1,218.96 and 428.25

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Solution

The fourth proportional to 813.81, 1,218.96 and 428.25 is: 641.45

Step by Step Solution

  1. Step 1: Write the proportion equation
    813.81 : 1,218.96 = 428.25 : x
  2. Step 2: Convert to fraction form
    813.81/1,218.96 = 428.25/x
  3. Step 3: Cross multiply
    813.81x = 1,218.96 × 428.25
  4. Step 4: Simplify right side
    813.81x = 522,019.62
  5. Step 5: Solve for x
    x = 522,019.62/813.81
  6. Step 6: Final answer
    x = 641.45

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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.