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Finding the Fourth Proportional to 689.47, 951.42 and 390.75

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Solution

The fourth proportional to 689.47, 951.42 and 390.75 is: 539.21

Step by Step Solution

  1. Step 1: Write the proportion equation
    689.47 : 951.42 = 390.75 : x
  2. Step 2: Convert to fraction form
    689.47/951.42 = 390.75/x
  3. Step 3: Cross multiply
    689.47x = 951.42 × 390.75
  4. Step 4: Simplify right side
    689.47x = 371,767.37
  5. Step 5: Solve for x
    x = 371,767.37/689.47
  6. Step 6: Final answer
    x = 539.21

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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.