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Finding the Fourth Proportional to 813.75, 1,123.12 and 638.79

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Solution

The fourth proportional to 813.75, 1,123.12 and 638.79 is: 881.64

Step by Step Solution

  1. Step 1: Write the proportion equation
    813.75 : 1,123.12 = 638.79 : x
  2. Step 2: Convert to fraction form
    813.75/1,123.12 = 638.79/x
  3. Step 3: Cross multiply
    813.75x = 1,123.12 × 638.79
  4. Step 4: Simplify right side
    813.75x = 717,430.82
  5. Step 5: Solve for x
    x = 717,430.82/813.75
  6. Step 6: Final answer
    x = 881.64

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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.