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Finding the Fourth Proportional to 1,218.76, 1,681.89 and 687.64

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Solution

The fourth proportional to 1,218.76, 1,681.89 and 687.64 is: 948.95

Step by Step Solution

  1. Step 1: Write the proportion equation
    1,218.76 : 1,681.89 = 687.64 : x
  2. Step 2: Convert to fraction form
    1,218.76/1,681.89 = 687.64/x
  3. Step 3: Cross multiply
    1,218.76x = 1,681.89 × 687.64
  4. Step 4: Simplify right side
    1,218.76x = 1,156,541.21
  5. Step 5: Solve for x
    x = 1,156,541.21/1,218.76
  6. Step 6: Final answer
    x = 948.95

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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.