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Finding the Fourth Proportional to 1,211.39, 1,671.77 and 687.47

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Solution

The fourth proportional to 1,211.39, 1,671.77 and 687.47 is: 948.74

Step by Step Solution

  1. Step 1: Write the proportion equation
    1,211.39 : 1,671.77 = 687.47 : x
  2. Step 2: Convert to fraction form
    1,211.39/1,671.77 = 687.47/x
  3. Step 3: Cross multiply
    1,211.39x = 1,671.77 × 687.47
  4. Step 4: Simplify right side
    1,211.39x = 1,149,288.28
  5. Step 5: Solve for x
    x = 1,149,288.28/1,211.39
  6. Step 6: Final answer
    x = 948.74

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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.