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Finding the Fourth Proportional to 640.48, 960 and 421.12

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Solution

The fourth proportional to 640.48, 960 and 421.12 is: 631.21

Step by Step Solution

  1. Step 1: Write the proportion equation
    640.48 : 960 = 421.12 : x
  2. Step 2: Convert to fraction form
    640.48/960 = 421.12/x
  3. Step 3: Cross multiply
    640.48x = 960 × 421.12
  4. Step 4: Simplify right side
    640.48x = 404,275.20
  5. Step 5: Solve for x
    x = 404,275.20/640.48
  6. Step 6: Final answer
    x = 631.21

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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.