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Finding the Fourth Proportional to 1,216.40, 1,678.62 and 685.30

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Solution

The fourth proportional to 1,216.40, 1,678.62 and 685.30 is: 945.71

Step by Step Solution

  1. Step 1: Write the proportion equation
    1,216.40 : 1,678.62 = 685.30 : x
  2. Step 2: Convert to fraction form
    1,216.40/1,678.62 = 685.30/x
  3. Step 3: Cross multiply
    1,216.40x = 1,678.62 × 685.30
  4. Step 4: Simplify right side
    1,216.40x = 1,150,358.29
  5. Step 5: Solve for x
    x = 1,150,358.29/1,216.40
  6. Step 6: Final answer
    x = 945.71

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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.