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Finding the Fourth Proportional to 1,221.39, 1,685.41 and 717.19

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Solution

The fourth proportional to 1,221.39, 1,685.41 and 717.19 is: 989.66

Step by Step Solution

  1. Step 1: Write the proportion equation
    1,221.39 : 1,685.41 = 717.19 : x
  2. Step 2: Convert to fraction form
    1,221.39/1,685.41 = 717.19/x
  3. Step 3: Cross multiply
    1,221.39x = 1,685.41 × 717.19
  4. Step 4: Simplify right side
    1,221.39x = 1,208,750.77
  5. Step 5: Solve for x
    x = 1,208,750.77/1,221.39
  6. Step 6: Final answer
    x = 989.66

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Half scale
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Double scale
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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.