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Finding the Fourth Proportional to 1,217.64, 1,680.31 and 686.69

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Solution

The fourth proportional to 1,217.64, 1,680.31 and 686.69 is: 947.60

Step by Step Solution

  1. Step 1: Write the proportion equation
    1,217.64 : 1,680.31 = 686.69 : x
  2. Step 2: Convert to fraction form
    1,217.64/1,680.31 = 686.69/x
  3. Step 3: Cross multiply
    1,217.64x = 1,680.31 × 686.69
  4. Step 4: Simplify right side
    1,217.64x = 1,153,840.24
  5. Step 5: Solve for x
    x = 1,153,840.24/1,217.64
  6. Step 6: Final answer
    x = 947.60

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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.