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Finding the Fourth Proportional to 911.89, 1,257.13 and 645.54

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Solution

The fourth proportional to 911.89, 1,257.13 and 645.54 is: 889.94

Step by Step Solution

  1. Step 1: Write the proportion equation
    911.89 : 1,257.13 = 645.54 : x
  2. Step 2: Convert to fraction form
    911.89/1,257.13 = 645.54/x
  3. Step 3: Cross multiply
    911.89x = 1,257.13 × 645.54
  4. Step 4: Simplify right side
    911.89x = 811,528.51
  5. Step 5: Solve for x
    x = 811,528.51/911.89
  6. Step 6: Final answer
    x = 889.94

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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.