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Finding the Fourth Proportional to 421.40, 631.64 and 318.35

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Solution

The fourth proportional to 421.40, 631.64 and 318.35 is: 477.17

Step by Step Solution

  1. Step 1: Write the proportion equation
    421.40 : 631.64 = 318.35 : x
  2. Step 2: Convert to fraction form
    421.40/631.64 = 318.35/x
  3. Step 3: Cross multiply
    421.40x = 631.64 × 318.35
  4. Step 4: Simplify right side
    421.40x = 201,082.58
  5. Step 5: Solve for x
    x = 201,082.58/421.40
  6. Step 6: Final answer
    x = 477.17

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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.