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Finding the Fourth Proportional to 1,187.82, 1,639.40 and 709.31

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Solution

The fourth proportional to 1,187.82, 1,639.40 and 709.31 is: 978.97

Step by Step Solution

  1. Step 1: Write the proportion equation
    1,187.82 : 1,639.40 = 709.31 : x
  2. Step 2: Convert to fraction form
    1,187.82/1,639.40 = 709.31/x
  3. Step 3: Cross multiply
    1,187.82x = 1,639.40 × 709.31
  4. Step 4: Simplify right side
    1,187.82x = 1,162,842.81
  5. Step 5: Solve for x
    x = 1,162,842.81/1,187.82
  6. Step 6: Final answer
    x = 978.97

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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.