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Finding the Fourth Proportional to 1,217.79, 1,680.39 and 686.70

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Solution

The fourth proportional to 1,217.79, 1,680.39 and 686.70 is: 947.56

Step by Step Solution

  1. Step 1: Write the proportion equation
    1,217.79 : 1,680.39 = 686.70 : x
  2. Step 2: Convert to fraction form
    1,217.79/1,680.39 = 686.70/x
  3. Step 3: Cross multiply
    1,217.79x = 1,680.39 × 686.70
  4. Step 4: Simplify right side
    1,217.79x = 1,153,923.81
  5. Step 5: Solve for x
    x = 1,153,923.81/1,217.79
  6. Step 6: Final answer
    x = 947.56

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1.5x scale

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.