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Finding the Fourth Proportional to 390.68, 586.38 and 287.66

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Solution

The fourth proportional to 390.68, 586.38 and 287.66 is: 431.75

Step by Step Solution

  1. Step 1: Write the proportion equation
    390.68 : 586.38 = 287.66 : x
  2. Step 2: Convert to fraction form
    390.68/586.38 = 287.66/x
  3. Step 3: Cross multiply
    390.68x = 586.38 × 287.66
  4. Step 4: Simplify right side
    390.68x = 168,675.14
  5. Step 5: Solve for x
    x = 168,675.14/390.68
  6. Step 6: Final answer
    x = 431.75

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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.