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Finding the Fourth Proportional to 491.47, 678.19 and 289.65

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Solution

The fourth proportional to 491.47, 678.19 and 289.65 is: 399.69

Step by Step Solution

  1. Step 1: Write the proportion equation
    491.47 : 678.19 = 289.65 : x
  2. Step 2: Convert to fraction form
    491.47/678.19 = 289.65/x
  3. Step 3: Cross multiply
    491.47x = 678.19 × 289.65
  4. Step 4: Simplify right side
    491.47x = 196,437.73
  5. Step 5: Solve for x
    x = 196,437.73/491.47
  6. Step 6: Final answer
    x = 399.69

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Why These Related Problems?

These problems maintain the same ratio (1.38) or explore similar proportional relationships. Practicing with related ratios helps build understanding of proportional relationships.