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Finding the Fourth Proportional to 1,286, 1,929 and 420.38

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Solution

The fourth proportional to 1,286, 1,929 and 420.38 is: 630.57

Step by Step Solution

  1. Step 1: Write the proportion equation
    1,286 : 1,929 = 420.38 : x
  2. Step 2: Convert to fraction form
    1,286/1,929 = 420.38/x
  3. Step 3: Cross multiply
    1,286x = 1,929 × 420.38
  4. Step 4: Simplify right side
    1,286x = 810,913.02
  5. Step 5: Solve for x
    x = 810,913.02/1,286
  6. Step 6: Final answer
    x = 630.57

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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.