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Finding the Fourth Proportional to 631.32, 870.96 and 398.40

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Solution

The fourth proportional to 631.32, 870.96 and 398.40 is: 549.63

Step by Step Solution

  1. Step 1: Write the proportion equation
    631.32 : 870.96 = 398.40 : x
  2. Step 2: Convert to fraction form
    631.32/870.96 = 398.40/x
  3. Step 3: Cross multiply
    631.32x = 870.96 × 398.40
  4. Step 4: Simplify right side
    631.32x = 346,990.46
  5. Step 5: Solve for x
    x = 346,990.46/631.32
  6. Step 6: Final answer
    x = 549.63

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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.