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Finding the Fourth Proportional to 639.99, 959.90 and 398.07

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Solution

The fourth proportional to 639.99, 959.90 and 398.07 is: 597.05

Step by Step Solution

  1. Step 1: Write the proportion equation
    639.99 : 959.90 = 398.07 : x
  2. Step 2: Convert to fraction form
    639.99/959.90 = 398.07/x
  3. Step 3: Cross multiply
    639.99x = 959.90 × 398.07
  4. Step 4: Simplify right side
    639.99x = 382,105.40
  5. Step 5: Solve for x
    x = 382,105.40/639.99
  6. Step 6: Final answer
    x = 597.05

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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.