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Finding the Fourth Proportional to 672.91, 1,009.80 and 399.40

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Solution

The fourth proportional to 672.91, 1,009.80 and 399.40 is: 599.36

Step by Step Solution

  1. Step 1: Write the proportion equation
    672.91 : 1,009.80 = 399.40 : x
  2. Step 2: Convert to fraction form
    672.91/1,009.80 = 399.40/x
  3. Step 3: Cross multiply
    672.91x = 1,009.80 × 399.40
  4. Step 4: Simplify right side
    672.91x = 403,311.60
  5. Step 5: Solve for x
    x = 403,311.60/672.91
  6. Step 6: Final answer
    x = 599.36

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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.