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Finding the Fourth Proportional to 665, 917.70 and 389

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Solution

The fourth proportional to 665, 917.70 and 389 is: 536.82

Step by Step Solution

  1. Step 1: Write the proportion equation
    665 : 917.70 = 389 : x
  2. Step 2: Convert to fraction form
    665/917.70 = 389/x
  3. Step 3: Cross multiply
    665x = 917.70 × 389
  4. Step 4: Simplify right side
    665x = 356,985.30
  5. Step 5: Solve for x
    x = 356,985.30/665
  6. Step 6: Final answer
    x = 536.82

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Why These Related Problems?

These problems maintain the same ratio (1.38) or explore similar proportional relationships. Practicing with related ratios helps build understanding of proportional relationships.