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Finding the Fourth Proportional to 685.81, 1,030.39 and 661.21

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Solution

The fourth proportional to 685.81, 1,030.39 and 661.21 is: 993.42

Step by Step Solution

  1. Step 1: Write the proportion equation
    685.81 : 1,030.39 = 661.21 : x
  2. Step 2: Convert to fraction form
    685.81/1,030.39 = 661.21/x
  3. Step 3: Cross multiply
    685.81x = 1,030.39 × 661.21
  4. Step 4: Simplify right side
    685.81x = 681,299.94
  5. Step 5: Solve for x
    x = 681,299.94/685.81
  6. Step 6: Final answer
    x = 993.42

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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.