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Finding the Fourth Proportional to 661.50, 991.89 and 430.47

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Solution

The fourth proportional to 661.50, 991.89 and 430.47 is: 645.47

Step by Step Solution

  1. Step 1: Write the proportion equation
    661.50 : 991.89 = 430.47 : x
  2. Step 2: Convert to fraction form
    661.50/991.89 = 430.47/x
  3. Step 3: Cross multiply
    661.50x = 991.89 × 430.47
  4. Step 4: Simplify right side
    661.50x = 426,978.89
  5. Step 5: Solve for x
    x = 426,978.89/661.50
  6. Step 6: Final answer
    x = 645.47

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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.