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Finding the Fourth Proportional to 661.09, 992.70 and 387.40

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Solution

The fourth proportional to 661.09, 992.70 and 387.40 is: 581.72

Step by Step Solution

  1. Step 1: Write the proportion equation
    661.09 : 992.70 = 387.40 : x
  2. Step 2: Convert to fraction form
    661.09/992.70 = 387.40/x
  3. Step 3: Cross multiply
    661.09x = 992.70 × 387.40
  4. Step 4: Simplify right side
    661.09x = 384,571.98
  5. Step 5: Solve for x
    x = 384,571.98/661.09
  6. Step 6: Final answer
    x = 581.72

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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.