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Finding the Fourth Proportional to 415.40, 619.64 and 389.88

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Solution

The fourth proportional to 415.40, 619.64 and 389.88 is: 581.57

Step by Step Solution

  1. Step 1: Write the proportion equation
    415.40 : 619.64 = 389.88 : x
  2. Step 2: Convert to fraction form
    415.40/619.64 = 389.88/x
  3. Step 3: Cross multiply
    415.40x = 619.64 × 389.88
  4. Step 4: Simplify right side
    415.40x = 241,585.24
  5. Step 5: Solve for x
    x = 241,585.24/415.40
  6. Step 6: Final answer
    x = 581.57

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Why These Related Problems?

These problems maintain the same ratio (1.49) or explore similar proportional relationships. Practicing with related ratios helps build understanding of proportional relationships.