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Finding the Fourth Proportional to 661.31, 991.96 and 430.76

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Solution

The fourth proportional to 661.31, 991.96 and 430.76 is: 646.14

Step by Step Solution

  1. Step 1: Write the proportion equation
    661.31 : 991.96 = 430.76 : x
  2. Step 2: Convert to fraction form
    661.31/991.96 = 430.76/x
  3. Step 3: Cross multiply
    661.31x = 991.96 × 430.76
  4. Step 4: Simplify right side
    661.31x = 427,296.69
  5. Step 5: Solve for x
    x = 427,296.69/661.31
  6. Step 6: Final answer
    x = 646.14

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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.