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Finding the Fourth Proportional to 421.50, 631.78 and 318.45

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Solution

The fourth proportional to 421.50, 631.78 and 318.45 is: 477.32

Step by Step Solution

  1. Step 1: Write the proportion equation
    421.50 : 631.78 = 318.45 : x
  2. Step 2: Convert to fraction form
    421.50/631.78 = 318.45/x
  3. Step 3: Cross multiply
    421.50x = 631.78 × 318.45
  4. Step 4: Simplify right side
    421.50x = 201,189.54
  5. Step 5: Solve for x
    x = 201,189.54/421.50
  6. Step 6: Final answer
    x = 477.32

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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.