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Finding the Fourth Proportional to 878.70, 1,212.64 and 485.70

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Solution

The fourth proportional to 878.70, 1,212.64 and 485.70 is: 670.28

Step by Step Solution

  1. Step 1: Write the proportion equation
    878.70 : 1,212.64 = 485.70 : x
  2. Step 2: Convert to fraction form
    878.70/1,212.64 = 485.70/x
  3. Step 3: Cross multiply
    878.70x = 1,212.64 × 485.70
  4. Step 4: Simplify right side
    878.70x = 588,979.25
  5. Step 5: Solve for x
    x = 588,979.25/878.70
  6. Step 6: Final answer
    x = 670.28

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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.