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Finding the Fourth Proportional to 631.40, 870.78 and 491.30

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Solution

The fourth proportional to 631.40, 870.78 and 491.30 is: 677.56

Step by Step Solution

  1. Step 1: Write the proportion equation
    631.40 : 870.78 = 491.30 : x
  2. Step 2: Convert to fraction form
    631.40/870.78 = 491.30/x
  3. Step 3: Cross multiply
    631.40x = 870.78 × 491.30
  4. Step 4: Simplify right side
    631.40x = 427,814.21
  5. Step 5: Solve for x
    x = 427,814.21/631.40
  6. Step 6: Final answer
    x = 677.56

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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.