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Finding the Fourth Proportional to 420.20, 628.95 and 328.40

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Solution

The fourth proportional to 420.20, 628.95 and 328.40 is: 491.54

Step by Step Solution

  1. Step 1: Write the proportion equation
    420.20 : 628.95 = 328.40 : x
  2. Step 2: Convert to fraction form
    420.20/628.95 = 328.40/x
  3. Step 3: Cross multiply
    420.20x = 628.95 × 328.40
  4. Step 4: Simplify right side
    420.20x = 206,547.18
  5. Step 5: Solve for x
    x = 206,547.18/420.20
  6. Step 6: Final answer
    x = 491.54

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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.