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Finding the Fourth Proportional to 287.09, 430.70 and 81.65

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Solution

The fourth proportional to 287.09, 430.70 and 81.65 is: 122.49

Step by Step Solution

  1. Step 1: Write the proportion equation
    287.09 : 430.70 = 81.65 : x
  2. Step 2: Convert to fraction form
    287.09/430.70 = 81.65/x
  3. Step 3: Cross multiply
    287.09x = 430.70 × 81.65
  4. Step 4: Simplify right side
    287.09x = 35,166.66
  5. Step 5: Solve for x
    x = 35,166.66/287.09
  6. Step 6: Final answer
    x = 122.49

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Why These Related Problems?

These problems maintain the same ratio (1.50) or explore similar proportional relationships. Practicing with related ratios helps build understanding of proportional relationships.