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Finding the Fourth Proportional to 667.09, 920.78 and 387.45

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Solution

The fourth proportional to 667.09, 920.78 and 387.45 is: 534.79

Step by Step Solution

  1. Step 1: Write the proportion equation
    667.09 : 920.78 = 387.45 : x
  2. Step 2: Convert to fraction form
    667.09/920.78 = 387.45/x
  3. Step 3: Cross multiply
    667.09x = 920.78 × 387.45
  4. Step 4: Simplify right side
    667.09x = 356,750.82
  5. Step 5: Solve for x
    x = 356,750.82/667.09
  6. Step 6: Final answer
    x = 534.79

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1.5x scale

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.