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Finding the Fourth Proportional to 390.40, 586.20 and 299.20

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Solution

The fourth proportional to 390.40, 586.20 and 299.20 is: 449.26

Step by Step Solution

  1. Step 1: Write the proportion equation
    390.40 : 586.20 = 299.20 : x
  2. Step 2: Convert to fraction form
    390.40/586.20 = 299.20/x
  3. Step 3: Cross multiply
    390.40x = 586.20 × 299.20
  4. Step 4: Simplify right side
    390.40x = 175,391.04
  5. Step 5: Solve for x
    x = 175,391.04/390.40
  6. Step 6: Final answer
    x = 449.26

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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.